The average per-semester cost of tuition, room and board at college prep schools is reported to be…

The average per-semester cost of tuition, room and
board at college prep schools is reported to be $8,500, but a
researcher believes that the average cost is higher. A study
conducted using 350 college prep school showed that the
average cost per semester is $8,745 with a standard deviation of
$1,200. Let = 0.05. What is the critical z-value for this test?