Statistics with confidence intervals

Question

A random sample of 80 college students was asked, “How many hours do you study each week?” After gathering the data, the sample has a mean of 14 hours and a standard deviation of 2.8 hours. Construct a 95% confidence interval for the mean number of hours all college students study per week

Answer 1

Confidence interval for mean = mean +/- z-critical * standard deviation/SQRT(sample size).

z-critical for a 95% confidence interval corresponds to the z-value for a probability of 0.975.