roastedchips wrote:

If x is a prime number, what is the number of different factors of 18x?

1) x^2 has 3 factors

2) x>3

the answer would depend on if x is a factor of 18, that is if x is 2 or 3If x is 2 or 3, Ans will be different ..

a) x=2, 18*2=\(2^2*3^2....(2+1)(2+1)=3*3=9\)

b) X=3, 18*3=2*3^3.......(1+2)(3+1)=3*4=12

If x is any other prime number, Ans will be different.

\(18x=2*3^2*X.......(1+1)(2+1)(1+1)=2*3*2=12\)

1) \(x^2\) has 3 factors.

Just tells us that \(x^2 is square of a prime number\)

This is already known

Insufficient

2) X>3

now X is a prime number >3

Irrespective of the value of X, factors of 18x will be

18x=2*3^2*X

So factors are (1+1)(2+1)(1+1)=2*3*2=12

Sufficient

B

_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372

2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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