Market Research

A university has 20,000 students, out of which 6000 are graduate students, and 14,000 are undergraduate students.

A researcher has drawn two separate simple random samples from the graduate students and the undergraduate students at this university.

Sample 1: 100 students were drawn from the graduate students at this university. On the average, these 100 students spent $500 on books in 2013.

Sample 2: 150 students were drawn from the undergraduate students at this university. On the average, these 150 students spent $800 on books in 2013.

Using the stratified sampling formula, estimate the average amount of money a student at this university spent on books in 2013. (Compute the estimate for the overall student population including graduate and undergraduate students.)