Question: For a population of 17 year old boys, the mean subscapular skinfold thickness is 9.7 mm and the standard deviation is 6.0 mm. What is the probability that the mean skinfold thickness for a simple random sample of 40 boys will be (a) greater than 11 mm?, (b) no more than 7.5 mm?, (c) between 7 and 10.5 mm?, (d) within 1 mm of the mean?