2013 AMC 10B Problem 9

Below is the professionally curated solution for Problem 9 of the 2013 AMC 10B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2013 AMC 10B solutions, or check the answer key.

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Concepts:prime factorizationgreatest common divisor

Difficulty rating: 1140

9.

Three positive integers are each greater than 1,1, have a product of 27000, 27000 , and are pairwise relatively prime. What is their sum?

100 100

137 137

156 156

160 160

165 165

Solution:

Only one of them is a multiple of 2,2, only one of them is a multiple of 3,3, and only one of them is a multiple of 5.5.

Since each of the positive integers is greater than 1,1, each of them must be a multiple of one of the given primes.

Therefore, since 27000=233353,27000=2^3\cdot 3^3\cdot 5^3, the numbers must be 23,33,53,2^3,3^3,5^3, making their sum 160.160.

Thus, the correct answer is D .

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