# Question

A vaccine to prevent severe rotavirus gastroenteritis (diarrhea) was given to African children within the first year of life as part of a drug study. The study reported that of the 3298 children randomly assigned the vaccine, 63 got the virus. Of the 1641 children randomly assigned the placebo, 80 got the virus.

a. Find the sample percentage of children who caught the virus in each group. Is the sample percent 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 0.05. Steps 1 and 2 of the hypothesis-testing procedure are given. Complete the question by doing steps 3 and 4.

Step 1: H0: pv = pp (pv is the proportion that got the virus among those who took the vaccine, and pp is the proportion that got the virus among those who took the placebo.) Ha: pv < pp

Step 2: Although we don’t have a random sample, we do have random assignment to groups.

a. Find the sample percentage of children who caught the virus in each group. Is the sample percent 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 0.05. Steps 1 and 2 of the hypothesis-testing procedure are given. Complete the question by doing steps 3 and 4.

Step 1: H0: pv = pp (pv is the proportion that got the virus among those who took the vaccine, and pp is the proportion that got the virus among those who took the placebo.) Ha: pv < pp

Step 2: Although we don’t have a random sample, we do have random assignment to groups.

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