Statistics a11

Assignment 11

1. CBU planner is interested in determining the percentage of spring semester students will

attend summer school. She takes a pilot sample of 160 spring semester students

discovering that 56 will return to summer school to take courses as well as engage in

some Christian activities on campus.

a. Construct a 88%, and 95% confidence interval estimate for the percentage of spring

semester student who will return to summer school

b. Using the results of the pilot study with a 0.88 and 0.95 probability, how large of a

sample would have to be taken to provide a margin of error of 3% or less?

2. The sales of a grocery store had a average of $8000 per day. The store introduced several

advertising campaigns in order to increase sales. To determine whether or not the

advertising campaigns have been effective in increasing sales, a sample of 64 days of

sales was selected. It was found that the average was $8,300 per day. From past

information, it is known that the standard deviation of the population is $1,200.

The researcher would like to test the following hypothesis

𝐻𝑜 : 𝜇 ≤ 8,000

𝐻𝑎: 𝑢 > 8,000

(a) Calculate the value of the test statistic. Let α=0.05

(b) What is the conclusion based on the critical value approach? Let α=0.05

(c) What is the conclusion based on the P-VALUE value approach? Let α=0.05