Question

Three athlete A, B and C participate in a race competition. The probability of winning A and B is twice of winning C. Then the probability that the race win by A or B, is

• A. 2/3
• B. ½
• C. 4/5
• D. 1/3

Answer 1

Answer: (C)

4/5

Answer 2

P(1) = P(2) = 2P(3)

P(1) + P(2) + P(3) = 1 ⇒ P(3) = 1/5 and P(1) = P(2) = 2/5

Hence P(AUB) = P(1) + P(2) = $\frac { 2 } { 5 } + \frac { 2 } { 5 } = \frac { 4 } { 5 }$