The scores on a standardized mathematics test for 8th-grade children in New York State form a normal distribution with a mean of m = 70 and a standard deviation of s = 10.
a. What proportion of the students in the state have scores less than X = 75?
b. If samples of n = 4 are selected from the popula- tion, what proportion of the samples will have means less than M = 75?
c. If samples of n =25 are selected from the popu- lation, what proportion of the samples will have means less than M = 75?