The number of viewers of American Idol has a mean of 21 million with a standard deviation of 10 million. Assume this distribution follows a normal distribution. Refer to the table in Appendix B.1. What is the probability that next week's show will:



(a) Have between 22 and 31 million viewers? (Round z-score computation to 2 decimal places and your final answer to 4 decimal places.)

1 answer

Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" (B1?) to find the proportions related to the Z scores.