Imagine You Are Estimating the Difference Between Two Population Means

Multiple Choice

Imagine you are estimating the difference between two population means by comparing 95% confidence intervals. If you use the 2SE rule of thumb and have desired margin of error of 5 cm, what is the approximate minimum sample size for each of the samples if the population standard deviation is 15 cm?

A) n = 108
B) n = 120
C) n = 132
D) n = 144