After scanning the UPC code of a 4 GB flash memory card using his smartphone, Michael Roth received the following prices for the goods at a variety of online retailers. Treat these data as a simple random sample of all online retailers. (5 points)
12, 13, 13, 14, 14, 15, 17, 19, 20, 21
a. Use a calculator with mean and standard deviation keys to find the sample mean year x and sample standard deviation s. Round your answer to the nearest whole number.
The sample mean: x̄ = _______ and sample standard deviation: s = _______.
b. Find a 95% confidence interval for the mean 4 GB flash memory card. What is the margin of error? Show formulas and round your answers to 2 decimal places.
Jennifer wants to estimate the proportion of students on her campus who read Bible daily. After surveying 32 students, she finds 25 who read Bible regularly. Obtain and interpret a 90% confidence interval for the proportion of students who read Bible daily on Jennifer's campus. (5 points)
a. Find a point estimate for p. Roud your answer to one decimal place.
b. Find a 90% confidence interval for p. What is the margin of error? Show formulas and round your answers to 2 decimal places.
c. Give a brief explanation of the meaning of your answer in the context of this problem.
d. Is the normal approximation to the binomial justified in this problem? Explain.