Question

You invite your best friend Sheila out for a picnic on Thursday. Sheila tells you "If it rains, there is a 20% probability

that I will come, but if it's sunny, there is an 80% probability that I will come." You check the weather and see that
there is a 40% chance of rain for that day. What is the overall probability that Sheila will attend your picnic? Explain
how you found your answer.

Answer 1

Answer: 56%

Probably that it will rain and she goes + probably that it will be sunny and she goes

= 0.4 * 0.2 + 0.6*0.8

= 0.08 + 0.48

= 0.56

56% chance