=+65. Let x denote the IQ of a child randomly selected from a certain large geographical region. Suppose x is known to have (approximately) a normal distribution with  5 15. A parent group wishes to test the hypothesis H0:  5 100 versus Ha:  . 100, hoping to reject the null hypothesis and be able to claim that the average IQ of their children exceeds the nationwide average. The test statistic in this situation is z 5 (x 2 100)y(15y1n).