Yesterday, Integrated Learning posted a 700 level GMAT question on our blog. Today, they have followed up with the answer:
Answer: B
If 100, which breaks down to 2252, is a factor of N, then a and b must be 2 and 5, though we don’t know which is which. What we do know is that there are either two 2’s and three 5’s, or the other way around, in N. The other prime factor (which is not 2 or 5) in N is c, and it only appears ONCE. 18=2×32 which would require the “other” prime 3 to appear twice. This cannot be. If you break down the other answers, you will see that each has some combinations of 2’s and 5’s, all of which could fit in N.
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