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rss GMAT Practice Question (One of Hundreds)
There are 7 "Nebraska" quarters, 6 "California" quarters, 4 "New Jersey" quarters, and 13 "Alabama" quarters in a sack. Karen is supposed to reach in and pick a quarter at random. She really wants a New Jersey quarter. What is the probability that she will get her wish?
Correct Answer: B
The probability of her wish coming true is the number of New Jersey quarters divided by the total number of quarters.
  1. There are 30 quarters in the sack (7+6+4+13).
  2. The probability that Karen gets her wish is P(New Jersey), which is (New Jersey Quarters)/(Total Quarters) = 4/30.
  3. Stated differently: There are 4 quarters, out of 30, that are New Jersey. So Karen has four possibilities of getting her wish.
  4. The fact she only gets to pick one quarter is not relevant. All that matters is what portion of the total number of quarters is the New Jersey version. So 4/30 quarters fit the bill. She also has 26/30 quarters that do not work. That means the correct response is 4/30, but you should reduce fractions when possible. That makes the correct response 2/15.
  5. Both C and D are large fractions not much less than 1. For either of those choices to be correct would mean she is almost certain to get her wished-for quarter. But logic should tell you the odds are slim. That leaves choices A and B.