According to a Recent Survey, Women Chat on Their Mobile

Short Answer

According to a recent survey, women chat on their mobile phones more than do men (CNN.com, August 25, 2010). Irina wants to estimate the difference between the average chat time for female and male college students. She takes a random sample of 40 male students and 40 female students in her college. She finds that female students chatted for a sample average of 820 minutes per month with a sample standard deviation of 160 minutes. Male students, on the other hand, chatted for a sample average of 760 minutes per month with a sample standard deviation of 240 minutes. You may assume that the population variances are equal.
A) Construct a 95% confidence interval for the difference between the population means.
B) Can we conclude that average chat time is different between female and male college students with 95% confidence?