GMAT prep integer problem

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GMAT prep integer problem

by subhasis8877 » Thu Jan 07, 2010 7:41 am
Please refer to the question attached
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by papgust » Thu Jan 07, 2010 9:11 pm
This is how i solved.

Value of a?

1. (a-7)(b-7)(c-7) = 0

This means that atleast one of values a,b,c must be 7. So, the product of this expression will be 0. But we don't know which one is 7. Insufficient.

2. bc = 18

Insufficient. No info about value a.

Combined,
bc = 2*3*3. We cannot have 7 in any of b and c. So, a must be 7 to satisfy the expression [(a-7)(b-7)(c-7) = 0].
Sufficient.