The ACT scores of applicants to college are approximately normally distributed with a mean of 20.3 and a standard deviation of 3.1. If a random sample of 20 applicants to college is chosen find the probability that their average ACT score will be 19 and 21.
2 answers
68%!
Here is the method.
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 scores.
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 scores.