The probability that Tom will win the Booker prize is 0.5, and the probability that John will win the Booker prize is 0.4. There is only one Booker prize to win. What is the probability that at least one of them wins the prize? (A) 0.2 (B) 0.4 (C) 0.7 (D) 0.8 (E) 0.9
My first approach: 1 - P (neither) = 1 - 0.5*0.6 = 0.7
Second approach: P(A) + P(B) - P(A and B) = 0.5 + 0.4 -0 = 0.9
Can someone please explain which one is correct and what is wrong with the other?