Thursday, September 09, 2010

If x is a positive integer, then how many factors does x have ?

(1) x is divisible by one more positive integer than 3^4 is.

(2) x is the product of three different prime numbers


From statement (1) - x has 5 factors 1, 3, 9, 27, 81. Adding one more factor from statement (1) makes total number

of factors to be six.
Thus x has 6 factors.
Hence sufficient

From statement (2) - x = abc where a, b, c are prime numbers. Thus in all x has 8 factors - 1, a, b, c, ab, bc, ac,

abc.
Thus x has 8 factors.
Hence sufficient


Note: Here each condition gives a different answer but still satifies the sufficient conditions.

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