Use the Following Information for Questions

Short Answer

Use the following information for questions:
College students spend a lot of their money, not on things they would like to buy, but on text books. College text books have increased in price significantly over the past few years. The amount students spend on text books is approximately normally distributed with a standard deviation of $50. The average amount spent on books each semester is $340 for undergraduate students and $250 for graduate students. Independent random samples of 100 undergraduate students and 80 graduate students are to be selected and the average amount they spent on text books last semester is to be compared (undergraduate - graduate).
-What is the expected value for the difference in sample means?