Question

"In one statistics course, students reported studying an average of 9.92 hours a week, with a standard deviation of 4.54. Treating this class as the population, what percent of students study more than 8 hours? (Round z score to two decimal places.)"

Answer 1

66.28% of students study more than 8 hours

Explanation:

The percent of students study more than 8 hour can be calculated as

P(X>8)=?

P(X>8)=P((X-mean)/sd>(8-9.92)/4.54)

The calculated z-score is -0.42.

P(X>8)=P(Z>-0.42)

P(X>8)=P(0<Z<-0.42)+P(0<Z<∞)

P(X>8)=0.1628+0.5=0.6628.

Thus, 66.28% of students study more than 8 hours.