Exactly one of Terry, Chris, and Kim will attend a party. The probability Terry attends is 0.31 and the probability Chris attends is 0.5. What is the probability that Kim attends?
A) 0.33
B) 0.5
C) 0.81
D) 0.19

Question

Quizplus · Accepted Answer

The sum of the probabilities of all possible outcomes must equal 1. Thus, the probability of Kim attending can be found by subtracting the sum of the probabilities of Terry and Chris attending from 1. 
Probability of Kim attending = 1 - (0.31 + 0.5) = 0.19. Therefore, the best choice is D, with a probability of 0.19.

Exactly One of Terry, Chris, and Kim Will Attend a Party