jmc

Question

Sheila has been invited to a picnic tomorrow. The picnic will occur, rain or shine. If it rains, there is a 20% probability that Sheila will decide to go, but if it is sunny, there is an 80% probability that Sheila will decide to go. The forecast for tomorrow states that there is a 40% chance of rain. What is the probability that Sheila will attend the picnic? Express your answer as a percent.

Accepted Answer

The probability that it rains and Sheila attends is (0.4)(0.2) = 0.08. The probability that it doesn't rain and Sheila attends is (0.6)(0.8) = 0.48. So the overall probability that Sheila attends is 0.08 + 0.48 = 0.56 = 56%.