Z = (score-mean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (.20) and its Z score. Insert data into above equation.
1 - .20 = ?
The National Center for Educational Statistics reported that in 2009 the ACT college placement and admission
examination were normally distributed and had a mean of 21.1 and standard deviation of 5.1. A college
requires applicants to have an ACT score in the top 20% of all scores. Find the lowest ACT score a student
could get to meet this requirement. Of five students picked at random from those taking the ACT, find the
probability that none score high enough to satisfy the admission standard.
1 answer
3 answers