Answer to Question #320369 in Statistics and Probability for Francis

Question

The division-wide aptitude test in

Mathematics was conducted to students.

The mean of the test is 58 and the standard

deviation is 12. The scores also approximate

the normal distribution. What percent of the

scores is between 55 and 65?

A. 9.87%

B. 18.23%

C. 21.90%

D. 31.77%

Answer 1

$P(55<X<65)=P(\frac{55-58}{12}<X<\frac{65-58}{12})=P(-0.25<X<0.58)=0.71904-0.40129=0.31775$