I am having trouble with these three questions:

IQ scores from the general population form a normal distribution with a m = 100 ands = 15. However, data indicate that children's intelligence may be affected by early exposure to lead. Using hospital records, a researcher obtained a sample of n = 121 children who had lead exposure. The average IQ for this sample wasx= 96. Do these data indicate that exposure to lead has a significant effect on IQ? Test withp=.05.

What is the level of significance?

Based on thelevel of significance you set in Step 1 (Question 5) and whether your alternative hypothesis is directional or non-directional, what is your decision rule? (In other words, what is your rejection region?)

Calculate the z statistic.