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2 votes
Please explain how to solve this please. The answer choices are listed in the image.

Please explain how to solve this please. The answer choices are listed in the image-example-1

1 Answer

6 votes

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.



User Keanu
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