According to a recent survey, women chat on their mobile phones more than men (CNN.com, August 25, 2010). In order to determine if the same patterns also exist in colleges, Irina 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. It is not reasonable to assume equal population variances.

a. Specify the competing hypotheses to determine if female students chat more, on average, than male students.

b. Calculate the value of the test statistic and itsp-value.

c. Make a conclusion at the 5% significance level.