1.The mean score of students on an aptitude test is 72 points with a standard deviation of 8 points. What is the probability that two groups of students, consisting of 28 and 36 students respectively, will differ in their mean scores by
(a) 3 or more points (b) 6 or more points?
2.The compressor of a refrigerator compressed saturated R-134a vapor at 5 F to 200 pisa. How much work (ft-lbf/lbm) does this require when the process is isentropic