21.35 Averages versus individuals. Scores on the ACT college entrance examination vary Normally with mean μ = 18 and standard deviation σ = 6. The range of reported scores is 1 to 36.
(a) What range contains the middle 95% of all individual scores?
(b) If the ACT scores of 25 randomly selected students are averaged, what range contains the middle 95% of the averages ?