A recent survey found that 63% of all adults over 50 wear glasses for driving. In a random sample of 20 adults over 50, what is the mean and standard deviation of the number who wear glasses? Round to the nearest hundredth when necessary.
A) mean: 12.6; standard deviation: 2.16
B) mean: 12.6; standard deviation: 3.55
C) mean: 7.4; standard deviation: 2.16
D) mean: 7.4; standard deviation: 3.55

Question

Quizplus · Accepted Answer

The mean is calculated as np = 20 * 0.63 = 12.6. The standard deviation is calculated as sqrt(np(1-p)) = sqrt(20 * 0.63 * 0.37) ≈ 2.16.

A Recent Survey Found That 63% of All Adults Over