1. A grading scale is set up for 1000 students' test scores. It is assumed that the scores are normally distributed with a mean score of 75 and a standard deviation of 15 a. How many students will have scores between 60 and 80? b. If 60 is the lowest passing score, how many students are expected to pass the test? 2. The shelf life of a particular cheese is normally distributed with a mean of 12 days and a standard deviation of 3 days. a. About what percent of the cheese lasts between 9 and 15 days? b. About what percent of the cheese lasts between 6 and 9 days?