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Last Updated on May 11, 2023
GMAT OFFICIAL GUIDE PS
Solution:
We are given a table with the following information:
Bag P has 37 marbles and 10.8% of those marbles are blue. So there are 0.108(37) = 3.996, or 4 blue marbles in bag P.
Bag Q has X marbles and 66.7% of those marbles are blue. Recall that the fraction 2/3 is approximately 66.7%, so there are (2/3)X blue marbles in bag Q.
Bag R has 32 marbles and 50% of those marbles are blue. So there are 0.5(32) = 16 blue marbles in bag R.
We are also given that 1/3 of the total marbles in the 3 bags are blue. Thus, we can create the following equation:
1/3(37 + X + 32) = 4 + (2/3)X + 16
Multiply the whole equation by 3, we have:
37 + X + 32 = 12 + 2X + 48
X + 69 = 2X + 60
X = 9
There are 9 marbles in bag Q.
Answer: B
