2003 AMC 12A Problem 8

What is the probability that a randomly drawn positive factor of

60

is less than

7?

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Solution

The number

60

has

12

positive factors:

1,2,3,4,5,6,

10,12,15,20,30,60.

Six of them are less than

7,

namely

1,2,3,4,5,6,

so the probability is

\dfrac{6}{12}=\dfrac12.

Thus, the correct answer is E.

Concepts: factor counting · basic probability

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