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number theory senior

Problem

What is the probability that a randomly drawn positive factor of is less than ?
(A)
(B)
(C)
(D)
(E)
Solution
For a positive number which is not a perfect square, exactly half of the positive factors will be less than . Since is not a perfect square, half of the positive factors of will be less than . Clearly, there are no positive factors of between and . Therefore half of the positive factors will be less than . So the answer is .
Final answer
E