how many students do you need to survey to estimate the mean sleep time of students at your university with 95% confidence and a margin of error of 0.8 hours?

Question

Suppose you want to conduct a similar study at your university. Assuming that the standard deviation of this sample is a reasonable estimate of the standard deviation of sleep time at your university, how many students do you need to survey to estimate the mean sleep time of students at your university with 95% confidence and a margin of error of 0.8 hours? Use Z = 1.96.

                    A) 18 students

                    B) 23 students

                     C) 20 students

                     D) 15 students

Answer 1

By condition z_c(σ/√n) is margin of error. So, 1.96(1.82/√n) = 0.8, n = 20 students.