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2003 AMC 12A Problem 8

Problem 8 of 25EasierNumber TheoryProbability & Statistics

What is the probability that a randomly drawn positive factor of 6060 is less than 7?7?

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Solution

The number 6060 has 1212 positive factors: 1,2,3,4,5,6,1,2,3,4,5,6, 10,12,15,20,30,60.10,12,15,20,30,60. Six of them are less than 7,7, namely 1,2,3,4,5,6,1,2,3,4,5,6, so the probability is 612=12.\dfrac{6}{12}=\dfrac12. Thus, the correct answer is E.
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