PSAT Math : How to find the probability of an outcome

Study concepts, example questions & explanations for PSAT Math

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Example Questions

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Example Question #86 : Probability

Aaron, Gary, Craig, and Boone are sitting down in a row of four chairs. What is the probability that Aaron and Gary will be seated beside each other?

Possible Answers:

Correct answer:

Explanation:

Consider first all of the possible ways the men may be arranged, which is

Now, consider all of the ways that Aaron and Gary could be seated beside each other; it may be easier to visualize by drawing it out:

  1. A G _ _
  2. G A _ _
  3. _ A G _
  4. _ G A _
  5. _ _ A G
  6. _ _ G A

As seen, there are six possibilities.

Finally, for each of these cases, Craige and Boone could be seated in one of two ways.

So the probability that Aaron and Gary will be seated beside each other is:

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