posted by Amy on .
The probability that a person has an unlisted telephone number is 0.15. The district manager of
a political action group is phoning people urging them to vote. In a district with 416 households, all households have phones. What is the probability that the district manger will find that:
(a) between 40 and 80 have unlisted numbers?
mean (most probable number) =0.15*416 = 62.4
sigma = sqrt(0.15*0.85*416) = 7.28
P (40 to 80) = 99.1%