An experiment has four possible outcomes: A, B, C, and D. Which of the following is a legitimate assignment of probabilities for these four events?
A) 0.3, 0.3, 0.3, 0.3
B) 0.2, 0.4, 0.1, 0.3
C) 0.6, 0.2, 0.3, -0.1
D) 0.2, 0.2, 0.4, 0.4

Question

Quizplus · Accepted Answer

In order for probabilities to be legitimate, they must add up to 1 and be non-negative. Choice B satisfies both conditions, with the probabilities adding up to 1 (0.2 + 0.4 + 0.1 + 0.3 = 1) and all probabilities being non-negative. Choices A, C, and D do not satisfy these conditions, with choices A and C having probabilities that do not add up to 1 and choice C having a negative probability.

An Experiment Has Four Possible Outcomes: A, B, C, and D