Select a sample of 20 individuals and the test the hypothesis =225 for IQ level. Use a=0.05

Answer 1

Your question is not clear.

How are you going to determine IQ level of the 20 persons? Would this relate to your inquiry?

Ho: mean = 100
Ha: mean > 100

If mean IQ = 100 and SD = 15 (as in WISC and WAIS):

Z = (score-mean)/SEm

SEm = SD/√n

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z score.