Probability of rain tomorrow is 80%. Probability of snow is 40%. Probability of rain and snow is 30%. What is the probability that it will rain or snow?

Question

This is a probability question. What are the steps to find the solution?

Answer 1

Since the "rain and snow" probability is an overlap of the overall probability of either, the breakdown is as follows:

 

Rain and snow: 30%

Rain alone: 80-30 or 50%

Snow alone: 40-30 or 10%

Total percentage of at least one: 30+50+10 or 90%

 

Looks like a good day to stay indoors tomorrow.

Answer 2

80 + 40 - 30 = 90%

 

P(A) + P(B) - P(A and B)