4 STAT HOMEWORK QUESTIONS

1.

A manufacturer withdrew Drug V from the market after a study revealed that its use was associated with an increase in the risk of heart attack. The experiment was placebo-controlled, randomized, and double-blind. Out of 1263 people taking Drug V there were 41 heart attacks, and out of 1288 people taking the placebo, there were 29 heart attacks. Perform a hypothesis test to test whether those who take Drug V have a greater rate of heart attack than those who take a placebo. Use a level of signicance of 0.10. Can we conclude that Drug V causes an increased risk of heart attack? Determine the hypotheses for this test. Let p1 represent the population proportion of heart attacks for those who take Drug V and let p2 represent the population proportion of heart attacks for those who take the placebo. Choose the correct answer below. A. H0:p1p2 .9 F. H02p1=p2 HA2p1=p2 HA: P1 =92 HAip1>p2 Find the test statistic for this test. 2: 1.538 (Round to three decimal places as needed.) Find the p-value for this test. pvalue = Cl (Round to three decimal places as needed.) A vaccine to prevent a severe virus was given to children within the first year of life as part of a drug study. The study reported that of the 3101 children randomly assigned the vaccine, 48 got the virus. Of the 1551 children randomly assigned the placebo, 40 got the virus. a. Find the sample percentage of children who caught the virus in each group. Is the sample percentage lower for the vaccine group, as investigators hoped? b. Determine whether the vaccine is effective in reducing the chance of catching the virus, using a significance level of 0.01. The first few steps of the hypothesis-testing procedure are given. Complete the procedure. i Click the icon to view the first few steps of the hypothesis-testing procedure. . . . . . a. Find the sample percentage of children who caught the virus in the vaccine group. 1.55 % (Round to two decimal places as needed.) Find the sample percentage of children who caught the virus in the placebo group. 2.58 % (Round to two decimal places as needed.) Is the sample percentage lower for the vaccine group, as investigators hoped? Yes O No b. Find the test statistic for this test. z= (Round to two decimal places as needed.)In a study, people were observed for about 10 seconds in public places. such as % malls and restaurants, to determine whether they smiled during the randomly Male Female chosen 10-second interval. The table shows the results for comparing males and Smile 3453 3932 females. Complete parts a through c below. No Smile 3748 4089 a. Find and compare the sample percentages of men who were smiling and women who were smiling. The percentage of men who were smiling in the sample was 47.95 %. (Round to two decimal places as needed.) The percentage of women who were smiling in the sample was 49.02 %. (Round to two decimal places as needed.) Compare the sample percentages. The percentage of people who were smiling was greater for the women. b. Treat this as though it was a random sample, and test whether there are differences in the proportion of men and the proportion of women who smile. Use a signicance level of 0.05. Determine the hypotheses for this test. Let p.I represent the population proportion of men who smile, and let p2 represent the population proportion of women who smile. Choose the correct answer below. 0 A. H0:p1=p2 O B. H02p1p2 HA5P192 HA3p1=p2 HA3P1=92 O o. H0:p1#p2 O E. Ho:p1=p2 O F- \"0:91:92 HA591=92 HA5P1>p2 HA5P1