試題詳解

39. A study is being conducted in which the health of two independent groups of ten policyholders is being monitored over a one-year period of time. Individual participants in the study drop out before the end of the study with probability 0.2 (independently of the other participants).
Calculate the probability that at least nine participants complete the study in one of the two groups, but not in both groups?
(A) 0.096
(B) 0.192
(C) 0.235
(D) 0.376
(E) 0.469