Question

The Census Bureau reports that 82% of Americans over the age of 25 are high school graduates. A survey of randomly selected residents of certain county included 1110 who were over the age of 25, and 871 of them were high school graduates.Find the mean and standard deviation for the number of high school graduates in groups of 1110 Americans over the age of 25.

Answer 1

Mean = 910.2

Standard deviation = 12.8

Explanation:

82% over the age of 25 are high school graduates.

A survey randomly selected students of certain country included 1110 who were over the age of 25 and 871 of them were high school.

n = 1110

p = 82% = 0.82

q = 1 - 0. 82

q = 0.18

Mean = np

= 1110*0.82

= 910.2

Standard deviation = √npq

= √ 1110*0.82*0.18

=√163.836

= 12.8