Carcass wrote:
Alice, Benjamin, and Carol each try independently to win a carnival game. If their individual probabilities for success are 1/5, 3/8, and 2/7, respectively, what is the probability that exactly two of the three players will win but one will lose?
A. 3/140
B. 1/28
C. 3/56
D. 3/35
E. 7/40
P(exactly 2 win) = P(A wins and B wins and C loses
OR B wins and C wins and A loses
OR A wins and C wins and B loses)
= P(A wins and B wins and C loses)
+ P(B wins and C wins and A loses)
+ P(A wins and C wins and B loses)
Let's calculate each probability
P(A wins and B wins and C loses) = P(A wins) x P(B wins) x P(C loses)
= 1/5 x 3/8 x 5/7
= 15/280
P(B wins and C wins and A loses) = P(B wins) x P(C wins) x P(A loses)
= 3/8 x 2/7 x 4/5
= 24/280
P(A wins and C wins and B loses) = P(A wins) x P(C wins) x P(B loses)
= 1/5 x 2/7 x 5/8
= 10/280
So, P(exactly 2 win) = 15/280
+ 24/280
+ 10/280
= 49/280
= 7/40
Answer: E
Cheers,
Brent