A study is done to determine if students in the California state university system take longer to graduate than students enrolled in private universities. One hundred students from both the California state university system and private universities are surveyed. From years of research, it is known that the population standard deviations are 1.5811 years and one year, respectively.

indicate which of the following choices best identifies the hypothesis test.

a. independent group means, population standard deviations and/or variances known

b. independent group means, population standard deviations and/or variances unknown

c. matched or paired samples

d. single mean

e. two proportions

f. single proportion