試題詳解

150. A theme park conducts a study of families that visit the park during a year. The fraction of such families of size m is , m = 1, 2, 3, 4, 5, 6, and 7.

For a family of size m that visits the park, the number of members of the family that ride the roller coaster follows a discrete uniform distribution on the set {1, … , m}.

Calculate the probability that a family visiting the park has exactly six members, given that exactly five members of the family ride the roller coaster.
(A) 0.17
(B) 0.21
(C) 0.24
(D) 0.28
(E) 0.31