The mean undergraduate cost for tuition, fees, room, and board for four-year institutions was $28,685 for a recent academic year. suppose that the standard deviation of the distribution is $4201 and that 50 four-year institutions are selected at random. find the probability that the sample mean cost for these schools is:

a. less than $26,000

b. greater than $30,000

c. between $27,000 and $31,000