At LLD Records, some of the market research of college students is done during promotions on college campuses, while other market research of college students is done through anonymous mail, phone, internet, and record store questionnaires. In all cases, the company solicits an "intent-to-purchase" score from the student, with 0 being the lowest score ("no intent to purchase") and 100 being the highest score ("full intent to purchase").

The manager finds the following information for 135 intent-to-purchase scores for a soon-to-be-released CD:

sample size sample mean sample variance
on campus 27 65 120.7
by mail 27 66 103.4
by phone 27 66.9 69.9
by internet 27 60.6 101.0
in a store 27 66.7 99.7

Suppose that the five populations of scores from which these samples were drawn are approximately normally distributed and have the same mean and the same variance.

Answer the following, carrying your intermediate computations to at least three decimal places and rounding your responses to at least one decimal place.

1. give an estimate of this common popualtion variance by pooling the sample variances given.

2. give an estimate of this common population variance based on the variance of the sample means given.