Consider the following scenarios where:
- r means "rained" which has a probability of .75
- N means "doesn't rain" which has a probability of .25
- * means it is irrelevant because the event already occurred
Scenario Probability
NN*** (.75)⁰(.25)² = .0625
rNN** (.75)¹(.25)² = .0469
rrNN* (.75)²(.25)² = .0352
rrrNN (.75)³(.25)² = .0264
TOTAL = .1710
This didn't produce one of your options, but .1875 is the closest.
ANOTHER WAY TO SOLVE:
(not rained)² x (rained)³ x Abar - # of times the event occurs
= (.25)² x (.75)³ x Abar - 4
The only problem with this method is that I don't know how to find Abar.
