-
yankee.musk
- Junior | Next Rank: 30 Posts
- Posts: 15
- Joined: Fri Feb 23, 2007 1:35 pm
- GMAT Score:610
(1) is not enough since it could be either 3, 6, 9...yankee.musk wrote:This is a GMATPrep problem
Is the integer n odd?
(1) n is divisible by 3
(2) 2n is divisible by twice as many positive integers as n
For some reason the spoiler feature is not working for me. So, OA is the answer choice # 3+5-1+2-7
(2) gonna do some tests
3*2=6.
6 is divisible by 1,2,3,6,
3 is divisible by 1,3
63*2=126
63 is divisible by 1, 3, 7, 9, 21, 63
1,2,3,7,9,21,63,126
so it doesn't tell us whether or not it's odd. this should also be impossible to tell with positive numbers. We can tell though, that it will only double the number of multiples. The total number of multiple will be 4 probably, because by multiplying a number by 2, you're adding 2 extra multiples (2, if 2 wasn't already a multiple) and the number that equals 2n.
so let's take a look at the multiples of 3.
3, 6, 9, 12.
lets look at their multiples.
1,3
1,2,3,6
1,3,9
1,2,3,4,6,12
together, with (1) and (2), the multiples of 2n are
1,2,3,6
1,2,3,4,6,12
1,2,3,6,9,18
1,2,3,4,6,8,12,24
as you can see, the answer could be either 9 or 3, so we can tell that together, we can't solve the problem, so E would be the answer.
