A recent survey found that 70% of all adults over 50 wear glasses for driving. In a random sample of 70 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: 21; standard deviation: 3.83
B)mean: 49; standard deviation: 3.83
C)mean: 49; standard deviation: 7
D)mean: 21; standard deviation: 7

Question

Quizplus · Accepted Answer

The mean of the number who wear glasses is found by multiplying the total number of adults by the percentage who wear glasses: 70 * 0.70 = 49. The standard deviation is calculated using the formula for the standard deviation of a binomial distribution, which is sqrt(n*p*(1-p)), where n is the sample size, p is the probability of success (in this case, wearing glasses). Thus, the standard deviation is sqrt(70*0.70*(1-0.70)) = 3.83.

A Recent Survey Found That 70% of All Adults Over