CombinatoricsDifficulty 2.0JuniorFind the answerUnited Kingdom
The positive integers from 1 to 150 inclusive are placed in a 10 by 15 grid so that each cell contains exactly one integer. Then the multiples of 3 are given a red mark, the multiples of 5 are given a blue mark, and the multiples of 7 are given a green mark. How many cells have more than 1 mark?
(A) 10 (B) 12 (C) 15 (D) 18 (E) 19
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