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9.1
In a curling match 40% of people using a red broom get the best score while 30% of people using a blue broom get the best score. Assume that this is true and take a random sample of 70 people using  a red broom and 421 people using a blue broom. Construct a confidence interval for the different proportion of people using red or blue brooms.

9.2
A study done by the pugh research institution took 2,001 high school sophomores and 2,500 high school juniors. The study showed that 600 high school sophomores were gang members while 1,300 high school juniors were gang members. Researchers wanna know if there is a difference in the number of high school sophomores and juniors that are in gangs.

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9.1: A recent study to determine whether or not heart disease was more common in men than in women performed a survey of 2136 men and 2314 women, which showed that 143 men and 156 women had heart disease. Let p1 = the true proportion of all men with heart disease and p2 = the true proportion of all women with heart disease. Check if the conditions for calculating a confidence interval for p1 - p2 are met.

9.2: A study of 230 high school sophomores and 256 high school juniors revealed that 134 sophomores and 121 juniors believe that the food in the cafeteria at their school is too expensive. Calculate the P-value using Table A or technology.

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A recent study regarding a groundbreaking new medicine states that the new product "x" decreases the chance of heart disease. Someone wanted to know if this pill works differently between males and females. In a test, 1500 randomly selected females received the pill while 1100 randomly selected males received the pill. In the male group, 970 of them ended up not having any heart problems while in the female group 1200 had no heart problems. Does this data give convincing evidence at a 95% confidence level that the new drug effects men differently then women?

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Two theaters are watching a movie. In theater 1, 120 people watched the movie and 100 people liked it. In theater 2, 154 people watched the movie and 132 people liked it. Find the 90% confidence interval for the difference in true proportions of people who liked the movie.

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This year 20,000 girls applied to a certain college and 21,000 boys applied to the same college. 6,480 girls got in and 6,200 boys got in. What is the 95% confidence interval for the difference between guys and girls acceptance.

A company has been experimenting with a new pain relieving drug. 36/50 people that took the drug noticed a difference and 14/50 people that took the placebo said they noticed a difference. Is there convincing evidence that the difference is greater than .05. Would the drug be accepted, that there is evidence that it is more effective than the placebo.

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9.1 Question
At a soccer game, 35 out of 69 randomly selected people were wearing sunglasses. At a rugby game occurring the same time playing across the street, 28 out of 54 randomly selected people were wearing sunglasses. Construct and interpret and 95% confidence interval for the different in proportion of people at the soccer game and at the rugby game who were wearing sunglasses.

9.2
A college counselor believes that Instructor A is more effective than Instructor B at preparing students to pass their midterm final. An incoming class of 500 students is randomly assigned to two groups, each of size 250. One group is taught by Instructor A, and the other is taught by Instructor B. At the end of the course, 144 of Instructor A's students and 172 of Instructor B's students pass the midterm exam. Do these results give convincing evidence at the 0.05 that Instructor A is more effective?

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9.2
Two dog trainers are arguing over whose better between them. Dog Trainer A believes he is better at training a dog to roll over than Trainer B. A group of 100 dogs come in to get trained, split into two groups of 50. One group is taught by instructor A, the other by instructor B. At the end of the training, 25 of instructor A’s dogs can roll over, while 40 of instructor B’s dogs can roll over. Do these results give convincing evidence at the a = 0.05 level that Instructor B is more effective?

9.1
In a survey, 230 of 350 randomly selected women preferred cats to dogs. In another survey, 335 of 350 randomly selected men preferred dogs to cats. Construct and interpret a 95% confidence interval for the difference in the proportion of men and women who prefer cats.

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9.1The teacher brings 2 large bags of candy. Bag 1 has 15% red candy. Bag 2 has 30% red candy. Bag 1 has SRS 100 pieces of candy and bag 2 has SRS 90 pieces of candy. P^1-p^2 is the difference between the sample proportions of red candy. Construct and interpret a 95% confidence interval for the difference in the true proportion of the 2 different bags?

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9.1
A t-shirt company wants to compare the durability of fabricating machines produced by two different manufactures. Employees randomly selected 200 t-shirts produced by each fabricator and find that 180 of the t-shirts produced by the first machine are acceptable and only 99 of the t-shirts produced by the second machine are acceptable. If p1 and p2  are the proportion of acceptable t-shirts produced by the first ad second machines, check if the conditions for calculating the confidence interval for p1-p2 are met!

9.2
A study by the Government surveyed random samples of 1000 forth grade students and 1000 fifth grade students in Washington. Results showed that 890 of the forth graders and 760 of the fifth graders eat candy on a daily basis. Researcher want to know if there's a difference in the kids energy in the forth graders and fifth graders. State a hypothesis for preforming a significance test and check the conditions for performing the test.

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David Mays, Ce-Lai Fong, Raz Fuchs

1) David and Raz are professional bean bag tossers. A total of 80% of Raz's bean bag tosses land through the hole while David only lands 75% through the hole. Suppose we take separate random samples of 50 bean tosses from Raz and David, and record the proportion of successful bean bag throws each person gets. Find the mean and standard deviation of the Sampling Distribution.

2) A sample survey interviews separate SRS of 600 female high school students and 450 male high school students. Researchers want to determine whether there is a difference in the proportion of male and female high school students who worked for pay last summer. In all, 310 of the females and 384 of the males say they worked for pay last summer. Let Pm and Pf be the proportions of all college males and females who worked last summer. What is the hypothesis that was tested? "=/" means not equal to
Ho:Pm-Pf=0 versus Ha:Pm-Pf=/(0
Ho:Pm-Pf=0 versus Ha:Pm-Pf>0
Ho:Pm-Pf=0 versus Ha:Pm-Pf<0
Ho:Pm-Pf=/0 versus Ha:Pm-Pf=0

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Nick Windle
Spencer Zeleny
1. At a football game, 57 of 85 randomly selected people own an Apple Watch. At a basketball game occuring across the street, 46 of 78 randomly selected people own an Apple Watch. Construct and interpret a 90% confidence interval for the difference in the proportion of people at the football and basketball game that own an Apple Watch.
2. A random sample of 250 of last year's very popular PS4 found that 40 PS4's had trouble downloading games. The Play Station company made an fix in hoping to fix the problem, and reduce the trouble. Then, they conducted a second random sample of 300 PS4's and 45 PS4's still had trouble downloading games on it. Does this data give convincing evidence at the o = 0.01 significance level that the Playstation Company was successful?

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A random sample of 100 of last year's model of a popular car found that 40 had a minor defect in the brakes. The car company made an adjustment in the production process to try to reduce the proportion of cars with the brake problem. A random sample of 350of this year's model found that 50 had the minor brake defect. Do these data give convincing evidence at the a= 0.05 significance level that the company's adjustment was successful?

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Elizabeth Fergus and Jack Deely 9.1 question

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Elizabeth Fergus and Jack Deely 9.1 question

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Congress wants to conduct a poll of the President's approval. They send out a survey to 10 people from each state, but only 7 people on average responded. Out of those 7 people, 3 approved in the first month and 4 approved after 5 months. Construct and interpret a 95% confidence interval for the change in the number of people who approve of the president from month 1 to month 5.

9.2 Question
Researchers wanted to see if out of 100 students whose parents did not attend college, went to college. 2 SRS of 500 from all over the country, found that 370 were first generation college students in the first SRS and 395 in the second SRS. Do these data give convincing evidence of a difference in the population proportions at the .05 significance level?

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9.1: In a poll, 345 of 530 randomly selected men were able to do the ABCs backwards. 468 of 503 women could as well. Construct and interpret a 99% confidence interval for the difference in the proportion of men and women who can do the ABCs backwards.

9.2: A random sample of last year's shoe model of 250 shoes found that 35 pairs had torn stitching. The shoe company made errors in the manufacturing of the shoe. The shoe company made a change to the manufacturing process to prevent this issue. A random sample of 500 of this year's shoes found that 30 had had the poor stitching. Does the data provided give convincing evidence at the 0.05 significance level that the company's adjustment was beneficial.

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9.2 A math tutoring company believes that tutor A is more effective than tutor B at preparing the students to pass their math classes. An incoming class of 200 students are randomly assigned to the two groups represented by the tutors.100 kids per tutor. At the end tutor A had 70 students that passed their math classes. Tutor B had 50 students that passed their math class. Do these results give convincing evidence that at the a=0.05 level, tutor A is better than tutor B?

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A surprising number of young adults (ages 15-20) still live in their parents' homes. The National Institutes of Health surveyed random samples of 2145 men and 2488 women in this age group and found that 978 of the men and 917 of the women lived with their parents. Construct and interpret a 99% confidence interval for the difference in the true proportions of men and women aged 19 to 25 who live in their parents' homes.

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Two English classes are taking a test. In class 1, 34 people took the test and 29 people passed. In class 2, 28 people watched the movie and 17 people passed. Find the 99% confidence interval for the difference in true proportions of students who passed the test.

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Bob Is a researcher for Ford trying to figure out how many cars have had problems within the first year. He takes a random sample of 100 owners of the 2016 models and learns that 23 Ford owners had problems in their first year of ownership. Bob then takes another random sample but for owners of the 2017 model. He finds that out of 230 cars, 57 of them had problems within the first year of ownership.

A) Construct and interpret a 95% confidence interval for the difference in the proportion of 2016 cars that had a problem in the first year and 2017 models that had a problem within the first year.

B) Based on your interval, is there convincing evidence of a difference in the true proportion of 2016 models and 2017 models with problems in the first year? Explain.

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A random sample of 100 of last year's model of a popular car found that 20 had a minor defect in the brakes. The car company made an adjustment in the production process to try to reduce the proportion of cars with the brake problem. A random sample of 270 of this year's model found that 50 had the minor brake defect. Do these data give convincing evidence at the A= 0.05 significance level that the company's adjustment was successful?

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In a random sample of 100 Krispy Kreme  customers, we found that 78 of the customers polled bought only glazed doughnuts. In a second sample from the local doughnut shop it was discovered that of 120 customers only 62 bought only glazed doughnuts. Find a 95% confidence interval for the difference in the true proportion of people who bought glazed doughnuts.

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A Coffee shop owner believes that the person who brews the coffee affects the taste and quality of the coffee. The owner then takes a random sample of 120 customers to come in and taste cups of coffee. He sends 60 customers to Steve, and 60 customers to Clark. By the end of the survey, 48 of Clark's customers enjoyed the cup of coffee, while only 37 of Steve's customers said they enjoyed the cup of coffee. Do these results give convincing evidence at the .05 level that Clark makes a better cup of coffee?

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9.1 In a random sample of 645 adults aged 25-30, 36% of adults considered themselves vegetarian. In a separate random sample of 655 adults aged 40-45, 19% of adults considered themselves vegetarian. Construct and interpret a 95% confidence interval for the difference between the true proportions of adult vegetarians in these age groups.
9.2 A random sample of 200 of last year's model of a popular phone found that 40 had minor defects in the battery. The tech company made adjustments to fix the defect. A random sample of 400 of this year's model found that 80 had the minor battery defect. Is this convincing evidence at  a 0.05 significance level that the adjustment was successful.

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9.2
A team of doctors have been testing a migraine pill. They are using a placebo and the real pill to test it's effectiveness. 81/100 people noticed a difference with the real pill and 67/100 people noticed a difference with the placebo pill. Is there convincing evidence that the difference between the two pills is greater that .05. Would the pill be believed to be more effective than the placebo?

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Nico and Kate                           At the local driving range, a golf club company displayed two separate types of clubs to be demoed. The first club was demoed by 35 random golfers, and 5 liked the clubs. Another random sample of 60 golfers demoed the second club and 16 liked the club. Does this data give convincing evidence at the a=0.05 significance level that more golfers liked the second club more than the first club?

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Nico and Kate                           At the local driving range, a golf club company displayed two separate types of clubs to be demoed. The first club was demoed by 35 random golfers, and 5 liked the clubs. Another random sample of 60 golfers demoed the second club and 16 liked the club. Does this data give convincing evidence at the a=0.05 significance level that more golfers liked the second club more than the first club?

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9.1 At beach 1, there were 57/100 people at the beach who were wearing a hat. At beach 2, there were 81/100 people who were wearing a hat. Construct and analyze a 95% confidence interval for the difference in proportions of people at beach 1 & 2 who were wearing a hat.

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At a local clothing store, they offer two different styles of shirts that are well made and cheap. The first style was liked by 52 shoppers, and preferred to buy 4 shirts. While the other style was liked by 65 shoppers and they preferred to buy 10 shirts. Does this data give convincing evidence at the a=.05 significance levels that more shoppers liked the first style compared to the second club?

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9.1
In a recent poll study, out of 690 men at a university 611 are right handed, and out of 709 women 503 are right handed. Construct a 95% confidence interval for the difference in proportion of men and women who are right handed at the university. Is there convincing evidence of a difference in the true proportions that men are more likely to be right handed at the university?

9.2
A study surveyed 2003 high school freshmen and 2609 high school seniors in California. Results showed that 1600 freshmen preferred mint chocolate ice cream to chocolate, and 2045 seniors preferred mint chocolate to chocolate. Researchers want to know if there is a difference in proportions of all California freshmen vs seniors who prefer mint chocolate ice cream. State appropriate hypotheses for performing a significance test, define parameters of interest. Check that the conditions for performing the test are met.

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9.1
Your teacher brings two large bags of skittles to class.  Bag 1 is 20% green skittles and Bag 2 is 15% green skittles.  Using a paper cup, your teacher takes an SRS of 60 skittles from Bag 1 and a separate  SRS of 60 skittles from Bag 2.  Let p1 and p2 be the difference in sample proportions of green skittles.  Construct and interpret a 95% confidence interval for the difference in proportion of the amount of green skittles in each bag.

9.2
A random sample of 150 of last year's model of a popular motorcycle found that 35 had a minor defect in the brakes. The motorcycle company made an adjustment in the production process to try to reduce the proportion of motorcycles with the brake problem. A random sample of 400 of this year's model found that 65 had a minor brake defect. Do these data give convincing evidence at the a=0.05 significance level that the company's adjustment was successful?

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(Julia & Mckenna)
At an A's game, 41 people out of a sample taken of 89 people bought churrros. At a Giants game, 23 people out of a sample taken of 67 poeple bought churros. Construct and interpret a 90% confidence interval for the different proportion of people at the A's and Giants game who bought churros.

9.2
A random sample of last year's Nike jackets of 306 found that 48 had faulty zippers. Since last year the Nike company has improved their quality of jackets. A random sample of 451 new jackets found that 23 had faulty zippers. Does the data provide convincing evidence, at the a=0.05 significance level, that Nike's improvement actually worked?

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9.1
Do younger people exercise more than older people? In a random sample of 788 adults aged 18-35, 45% exercised at least once a week. In a separate random sample of 765 adults aged 35-50, 19% excercised at least once a week. Construct and interpret a 99% confidence interval for the difference between the true proportions of adults in these age groups who exercise.

9.2
A study from the Nationwide Drug Association surveyed random samples of 1,263 college freshmen and 1,432 college seniors in Nevada. Results showed that 243 of the college freshman and 960 of the college seniors had used had used recreational drugs at least 5 times. Researchers want to know if there is a difference in the proportion of all Nevada college students who have used recreational drugs. Check to see that the conditions for performing the test are met.

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9.1
In random sample of 640 male high school students who have tardies, 530 of them had more than 10. In a separate random sample of 610 female high school students with tardies, 523 of them had over 10 tardies. Construct and interpret at 95% Confidence interval for the difference between the proportion of male and female students who have over 10 tardies.
9.2
The owner of a company believes that machine A is more effective than machine B in making shoes. In a group of 200 shoes, 100 shoes are assembled by each machine. At the end of the work day Machine A correctly assembled 50 shoes, while Machine B correctly assembled 32 shoes. Do these results at the 0.05 confidence level that machine A is more efficient.

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9.1
Do younger people go out to eat more than older people? In a random sample of 600 adult yelp users aged 18-30, 48% said they go out to eat on average three times a week. In a separate random sample of 580 adult yelp users aged 31-50, 32% said they go out to eat on average three times a week. Construct and interpret a 95% confidence interval for the difference between the true proportions of adult yelp users in these age groups who go out to eat on average 3 times a week.

9.2
A gym owner believes Personal Trainer X effective than Personal Trainer Y at helping personal training clients reach their goals. A group of 50 new clients are randomly assigned into two groups, 25 to each trainer. At the end of a three month period training three times a week with their assigned trainer,  21 of Trainer X's clients and 19 of Trainer Y's clients reached their goals. Do these results give convincing evidence at the a=0.05 level that Trainer X is more effective?

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9.1 A random sample of 200 fast food customers showed that 150 of them order a soda with their meal. At a restaurant across town at the same time, 90 out of 200 randomly selected customers ordered soda with their meal. Construct and interpret a 95% confidence interval for the difference in proportion of people at the fast food place and the restauraunt who ordered soda with their meal.
9.2 A study by a psychologist surveyed random samples of 200 female patients and 300 male patients in Tennessee. Results showed that 120 of the female patients and 100 male patients bite their nails to cope with anxiety. State a hypothesis for performing a significance test and check the conditions for performing the test.

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9.1: in a recent study, 340 out of 460 randomly selected men in the US were able to identify France when it was highlighted on a map of Europe. When 390 selected women were asked, 160 were able to do so. Construct and interpret a 95% confidence interval for the difference in the proportion of US men and women who can identify France on a map? Explain.

9.2: Which drug is more effective at lowering chances of getting cardiovascular disease, drug 1 or drug 2. They used 2000 people to test this study, and came to find the proportion(.253) for the 1200 people who chose drug 1 died after 10 years. The proportion for drug 2 was (.213). Does this study provide convincing evidence of a difference in the effectiveness of Drug 1 and Drug 1?

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9.1
In a random sample of 672 adult Internet users aged 18 to 29, 44% used Instagram. In a separate random sample of 657 adult internet users aged 30 to 49, 11% used Instagram. Construct and Interpret a 95% confidence interval for the difference between the true proportions of adult Internet users in these age groups who use Instagram.
9.2
In a study of 4000 randomly selected teenagers in 2001, 630 showed some eyesight loss. In a similar study of 2000 teenagers reported in  2013, 480 showed some eyesight loss. Do these data give convincing evidence that the proportion of all teens with eyesight loss had increased at the α=0.02 significance level?

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The EPA wants to know if there is a difference in preference of natural trees between urban and rural households. So, the EPA sponsored a survey of California households that had a natural tree last year to find out. In a random sample of 160 rural households 64 had a natural tree. In a separate
Random sample of 261 urban households, 89 had a natural tree. A 95% confidence interval for the true difference in the proportion of households that had a natural tree is -0.036 to 0.154. Does this confidence interval provide convincing evidence that the two population proportions are equal? Explain.

A High School principal believes that Teacher A is more effective than Teacher B at preparing students to pass the California Exit Exam. The incoming class of test takers of 100 students is randomly assigned to two groups, each of size 50. One group is taught by Teacher A; the other is taught by Teacher B. At the end of the course, 30 of teacher A’s students and 22 of teacher b’s students passed the exit exam. Do these results give convincing evidence at the (alpha) = 0.05 level that Teacher A is more effective?

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9.1
At an SRV rally, 345 of 405 randomly selected students own an iPhone. At a MV rally happening across town, 370 out of 420 randomly selected students own an iPhone. Construct and interpret a 99% confidence interval for the difference in the proportion of people at the SRV rally and at the MV rally who own an iPhone.
9.2
A study conducted by scientists surveyed 1000 randomly selected juniors and 1000 randomly selected seniors from schools in Missouri. Results showed that 683 juniors drank coffee every morning and 795 seniors drink coffee every morning. The scientists want to know if there's a difference in the students energy. State a hypothesis for preforming a significance test and check the conditions for performing the test.

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9.1
At a basketball game, 38 of 82 randomly selected people drive a car. At a popular restaurant down the street, 24 of 64 randomly selected people drive a car. Construct and interpret a 95% confidence interval for the difference in the proportion of people at the basketball game and the people at restaurant that drive a car.

9.2
A principal at a high school believes that Teacher B is better than Teacher A at teaching math and preparing students to pass a test. An incoming class of 60 students is randomly assigned to one of the teachers, both in sizes of 30. One group is taught by Teacher A and the other by Teacher B. At the end of the class period, 13 of Teacher A's students and 18 of Teacher B's students passed the test. Do these results give convincing evidence at the 0.05 level that Teacher B is more effective

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9.1
For testing out a new trial drug for leukemia, a lab decided to test its effect on a random group of leukemia patients. The patients were randomly assigned either a new drug or a placebo. After monitoring the effects for several months, the lab found that 43 of the 213 patients who received the drug went into remission while only 12 out of the 206 patients that received the placebo went into remission. Construct and interpret a 95% confidence interval for a difference between the effectiveness of the drug and the placebo

9.2
Refer to the previous question for 9.1. Is there convincing evidence that the drug has positive effects on the population at the 0.01 significance level?

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9.1
In a 2009 survey, researchers asked if California residents approved of a new law before and after it was enacted. Of 800 people surveyed before the law was enacted, 550 supported it. After the law was enacted, of 800 people surveyed, 720 approved of the new law. Construct and interpret a 90% confident interval for the difference between the two proportions of residents who approved the law before and after it was enacted.

9.2
A principal believes that students in teacher A's class are more likely to passed the school standardized exam than students in teach B's class. To test this theory, the principal checks the scores and finds 24 of the 29 students in teacher A's class passed and 17 of the 23 students in teacher B's class passed the exam. Do these results give convincing evidence at the a=.01 level that teacher A's students are more likely to pass the exam

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At a Chess tournament at Diablo Valley College, 69 of 100 randomly selected people say they prefer igneous rock over sedimentary rock. At an Animal Rights Club meeting occurring at the same time across town at San Ramon Valley High School, 82 of 100 randomly selected people prefer igneous rock over sedimentary rock. Construct and interpret a 95% confidence interval for the difference in proportion of people at a DVC Chess tournament and at an SRVHS Animal Rights Club meeting who prefer sedimentary rock over sedimentary rock.

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9.1
In a recent study, we discovered that men are statistically more likely to drink coffee than girls on a regular basis. A random sample of 1000 people were taken. Out of the 542 men 212 of them drank coffee on a regular basis, and out of the 458 women 190 drank coffee on a regular basis. Construct a 95% confidence interval for the different proportion of people who drink coffee regularly.

9.2
A random sample of 500 people were taken from a pool and were asked if they like Disneyland. 362 of them said they did and 138 people in the sample said they did not. They were then asked if they consider themselves to be happy on a regular basis. 225 of the people who like Disneyland do consider themselves happy, and 78 of people who say they don't like Disneyland say that they do consider themselves happy. State a hypothesis for performing a significance test and check the conditions for performing the test.

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9.1
In a past poll, 7069 babies out of a total of 7669 were allowed to attend the annual Michael Vick doggy day care fundraiser. Out of a total of 6999 adults, 5069 of them were also able to attend the fundraiser. Construct a 95% confidence interval to discover the difference in proportion of babies and adults who attended Michael Vick's annual doggy day care fundraiser.

9.2

A study surveyed 3456 girls and 5432 boys at a carnival. Results showed that 789 girls preferred fried watermelon, and 678 boys preferred fried watermelon. Researchers want to know if there is a difference in proportions of boys and girls who prefer fried watermelon at a carnival. Does the data provide convincing evidence at the a=0.05 significance level that more girls prefer fried watermelon?

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9.1
In a recent study done by Collegeboard, out of the SRV class of 500, 110 females out of 300 got into UC's and 97 males out of 200 got into UC's. Construct a 95% confidence interval for the difference in proportion of females and males that got into UC's.

9.2
A study by Food Critic Association studied a random group of people in San Francisco to see their food preferences. Results showed that 189 females out of 400 preferred Italian food to Fast food while 237 out of 540 men preferred Italian to Fast Food. Researchers want to know if there is a difference in proportion of men vs women who prefer Italian over Fast food. State an appropriate hypotheses for performing a significance test and define the parameters of interest. Check that the conditions for performing the test are met.

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9.1
In a recent study at University Youdidnotgetin, students were concerned about the correlation between hot sauce and aggression. In a random sample of 2,000 students at the school , of which 1,000 students were observed consuming sriracha (a milder sauce) and the other 1,000 observed consuming Ghost pepper sauce( extremely hot). 450 of the sriracha group were immediately more irritable after two hours after consumption, compared to 600 of the ghost pepper. Let p1= the true proportion of students whose aggressive behavior is caused by sriracha consumption, and let p2= the true proportion of students whose aggressive behavior is caused by ghost pepper sauce consumption. Check if the condition of calculating the confidence Interval for p1 and p2 are met.
9.2
In a random study of 750 teenagers , male and female, at a local California high school, 300 regularly bleach their hair while 450 do not. Administrators wanted to investigate the effect of regular use of bleach on a teenager's IQ score, measured in number of points deviated from the average score of 100. Of the 300 teenagers, 100 were reported to deviate by 10 points from the average IQ score, while 88 of 450 teenagers were reported to deviate by 10 points from the average IQ score. Do these results give convincing evidence at a=0.05 level that regular use of hair bleach has an effect on teenagers IQ scores?

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9.1
Do younger people sleep less than older people? In a random sample of 500 people aged 18-30 and 500 people aged 48-60. 65% of those ages 18-30 slept less than 8 hours per day, while 30 % of those aged 48-60 slept less than 8 hours per day. Construct and interpret a 99% confidence interval for the difference between the true proportions of young and old people's average hours of sleep.

9.2
In a recent study conducted by the British Center for Cookie Development (BCCD) 450 people were asked if they prefer chocolate chip cookies or snickerdoodle cookies more. 297 people preferred chocolate chip and 153 people preferred snickerdoodles. Do these results give convincing evidence at the a=0.05 level that chocolate chip cookies are more preferred by the majority of the British population?

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9.1
At a zoo, 14 fish out of the random sample of 60 fish eat other fish. At the aquarium, a random sample of 70 fish out of 79 eat other fish. Construct and interpret a 95% confidence interval for the difference between the true proportions of fish at the zoo and at the aquarium who eat other fish.
9.2
A study at a North Dakota middle school surveyed random samples of 57 sixth graders and 99 eighth graders. Results showed that 30 the sixth graders and 89 of the eighth graders were addicted to caffeine. Researchers are curious to know if there is a difference in proportion of all middle school sixth graders and eighth graders who are addicted to caffeine.
a)Calculate the standardized test statistic.
b)Find the P-value using Table A or technology.

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9.1
A corporation that sells used cars wants to compare the reliability of car manufactures produced by two different companies. The corporation records 400 cars made by each manufacturer. They find that 360 cars produced by the first manufacturer have no flaws, and 385 cars of the second manufacturer have no flaws. Calculate the confidence interval between p1 and p2.
9.2
The board of education at the local high school set out to find if studying helps students pass more tests. To answer this question, the board took a sample of 500 students take a test. Group A with 250 students did not study for the test, while Group B with 250 students studied an hour a night for a week before the test. The results of the test showed that in Group A 120 had passed the test, and in Group B 225 passed the test. Does this provide convincing evidence that studying before a test helps students pass the test?

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9.1
A company that makes DVDs is testing the reliability two different DVD manufacturing machines. Employees randomly select 400 dvds made by each machine and find that 360 made by the first machine are acceptable and 340 made by the second machine are acceptable. construct a 99% confidence interval for the difference in proportion of the the two machines
9.2
A baking school owner believes that Instructor A is ore effective than Instructor B at preparing the students to pass the Get Baked exam on baking. An incoming class of 90 students is randomly assigned into two groups.one group gets A, one groups gets B. At the end of the course, 40 of instructor A's passed, and 30 of instructor B's passed. Do these results at a 0.5 significance level give convincing evidence that instructor B is more effective?

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9.1
Two researchers for the Dazzling Dye hair dye company wanted to see if there was a difference between customers ages 14-18 who bought their Electric Blue hair dye and customers ages 19-23 who bought Electric Blue hair dye. They randomly selected 700 customers and asked their ages, then asked if they bought Electric Blue. they found that out of the 324 customers ages 14-18, 149 of them bought the dye. Of the 376 older customers, only 87 bought the dye. Construct and interpret a 95% confidence interval for the difference in proportion of 14-18 year olds who bought Electric blue and 19-23 year olds who bought Electric Blue.

9.2
In a recent study, a comedian wanted to find out the difference between how many men and women died of laughter during his performances. He randomly selected 9,000 men and 8,900 women who had previously attended any of his performances and found that 60 men and 25 women died of laughter. State appropriate hypotheses for performing a significance test, define parameters of interest, and check to see if the conditions for performing this test are met.

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9.1
At a baseball game, 12 out of 49 randomly selected people own an Android phone. At a softball game, 34 out of 56 randomly selected people own an Android. Construct and interpret a 99% confidence interval for the difference in the proportion of people at the baseball game and at the softball game.
9.2
A study by the NFL surveyed random samples of 450 retired non hall of fame athletes and random samples of 215 hall of fame athletes. The survey showed that 22 non hall of fame athletes and 14 hall of fame athletes used Human Growth Hormones(HGH) during  their career. The NFL wants to know if there is a difference between the proportion of non hall of fame athletes and hall of fame athletes that used Human Growth Hormones(HGH) during their career.
A) check to see if the conditions for performing the test are met.
B) Construct and interpret a 95% confidence interval for the difference in the proportion of non hall of fame athletes and hall of fame athletes that used HGH in their career.

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9.1
Who spends more time on their phones: men or woman? A recent study conducted by World Tech Inc. studied 500 males (group 1) with ages ranging from 18-60 and learned that 367 of them use their phones for 5+ hours a day.  The second study was conducted on 500 females (group 2) showed that 426 of them use their phones for 5+ hours a day. Construct a 95% confidence interval for the difference in proportion of men and woman who spend 5+ hours daily on their phones. Is there convincing evidence of a difference in the true proportion that woman are more likely to spend 5+ hours daily on their phones?

9.2
A random sample of 500 people were taken and asked if they like going to Disneyland or not. They were then asked if they consider themselves to be happy on a regular basis. Out of the 354 people who like going to Disneyland 220 of them consider themselves to be happy on a regular basis. Out of the 155 people who don't like going to Disneyland 74 of them said that they consider themselves to be happy on a regular basis. State an appropriate hypothesis for performing a significance test, and define the parameters of interest.

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9.1
At a local high school, a random sample of 64 out of 100 juniors claimed to have self diagnosed anxiety. In the senior class, 58 out of 93 students claimed to have self-diagnosed anxiety. Is there convincing evidence, that at a 99% confidence interval, there is a difference in proportion of the numbers of juniors and seniors that have self-diagnosed anxiety?

9.2
In a recent random study at a movie theater, it was concluded that 71 out of 100 men preferred action movies over comedy movies, while 83 out of 104 females preferred comedy movies over action movies. Is there convincing evidence that at a .05 alpha level, there is a difference between the proportions of men and women that prefer action movies over comedy movies?

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9.1
In a sweeping match 40% of people using a red broom get the best score while 30% of people using a blue broom get the best score. Assume that this is true and take a random sample of 70 people using  a red broom and 421 people using a blue broom. Construct a confidence interval for the different proportion of people using red or blue brooms.

9.2
A study done by the Stowers Research Institution took 2,001 high school freshman and 2,500 high school seniors. The study showed that 600 high school sophomores were gang members while 1,300 high school freshman were gang members. Researchers wanna know if there is a difference in the number of high school seniors and juniors that are in gangs.

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9.2
In a Past study at Harvard University, a random 705 men and 543 women were asked which color they liked more, red or blue. Out of the 705 men, 400 said they like red better. Out of the 543 women, 310 said they liked red more.  Researchers want to know if there is a difference in men and women at Harvard University who prefer the color red over blue. State appropriate hypotheses for performing a significance test and check that the conditions for performing the test are met.

9.1
At a football game, 90 out of 170 randomly selected people were wearing spirit wear for the SRV wolves. On the other side of the stands 65 our of 170 randomly selected people were wearing spirit wear for Monte Vista. Construct and interpret a 99% confidence level for the difference in proportion of people supporting the wolves and the other supporting the Mustangs.