Problem Solving

BTGmoderatorDC wrote:Each of the items in a box is either a ball or a cube and each item is either red or blue. 72% of the items are cubes and 54% of the items are blue cubes. What percent of the cubes are red?

(A) 18%
(B) 25%
(C) 46%
(D) 50%
(E) 54%

OA B

Source: EMPOWERgmat

Given that 72% of the items are cubes, we have

% of blue cubes + % of red cubes = 72%

=> 54% + % of red cubes = 72%

=> % of red cubes = 72% - 54% = 18%

The correct answer: A

Hope this helps!

-Jay
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The above solution isn't right. If we have 100 objects, we have 72 cubes. If 54 of these are blue, the rest, or 18, are red. The question asks "What percent of the cubes are red?", and we have 18 red cubes and 72 cubes in total, so the answer is 18/72 = 1/4 = 25%.

BTGmoderatorDC wrote:Each of the items in a box is either a ball or a cube and each item is either red or blue. 72% of the items are cubes and 54% of the items are blue cubes. What percent of the cubes are red?

(A) 18%
(B) 25%
(C) 46%
(D) 50%
(E) 54%

OA B

Source: EMPOWERgmat

We can assume there are 100 items in the box. Thus, 72 items are cubes and 28 items are balls. Furthermore, 54 items are blue cubes, and hence 72 - 54 = 18 cubes are red. Therefore, the percent of cubes that are red is:

18/72 x 100 = 1/4 x 100 = 25

Answer: B