Question

A recent survey found that 76 ​% of all adults over 50 wear glasses for driving. in a random sample of 100 adults over​ 50, what is the mean and standard deviation of those that wear​ glasses? round the answers to the nearest hundredth.
a. ​mean: 24.00 ​; standard​ deviation: 4.27
b. ​mean: 76.00 ​; standard​ deviation: 8.72
c. ​mean: 24.00 ​; standard​ deviation: 8.72
d. ​mean: 76.00 ​; standard​ deviation: 4.27

Answer 1

Mean = np = 60(0.7) = 42

Standard deviation = sqrt(npq) = sqrt(60(0.7)(0.3)) = 3.55