Use the normal distribution of SAT critical reading scores f

Use the normal distribution of SAT critical reading scores forwhich the mean is 503 and the standard deviation is 125. Assume thevariable x is normally distributed. A) What percent of the SAT verbal scores are less than 625? B) If 1000 SAT verbal scores are randomly selected about howmany would you expect to be greater than 525 ?

Solution

X n(503, 125)

a)

P(X 625) = P((X - 503)/125 (625 - 503)/125) = P(Z 0.976) = 0.8340*100 = 83.40%

b)

P(X 525) = P((X - 503)/125 (525 - 503)/125) = P(Z 0.176) = 0.5675*1000 = 567