The Census Bureau reports that 82 of Americans over the age

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 1380 who were over the age of 25, and 1147 of them were high school graduates. Find the mean and standard deviation for the number of high school graduates in groups of 1380 Americans over the age of 25. Is that county result of 1147 unusually high, or low. or neithor? (Enter HIGH or LOW or NEITHER)

Solution

Ans(a):

n = 1380; p = 0.82; q = 0.18;
Mean = = (n p) = 1131.6;

standard deviation = = ( n p q ) = ( 1131.6* 0.18 ) = 14.2719304931
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Ans(b):

z = ( x - ) /

P ( x < 1147) = P ( z < (1147-1131.6)/14.2719304931 ) = P ( z < (1.07904112954)

=P ( z < (1.08))

=1-0.1401=0.8599

since 86% of 1380 is 1187 which is more than 1147 so it will be LOW