Hi guys,
Got this one after 12 correct in a row. It was my question nr. 20 and I believe this one belongs to the 700's level. I got 49 on Quant. in this Prep.
I'll post OA later.
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GMAT Prep 700's level
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Ans is A.
1) (3y+7)y = x => x is a multiple of y. Sufficient
2) x(x-1) = ny ( x(x-1) is a multiple of y).
x = ny/(x-1)...now it not necessary that x is a multiple of y. Insufficient.
Thus, A
I hope it helps
Amit
1) (3y+7)y = x => x is a multiple of y. Sufficient
2) x(x-1) = ny ( x(x-1) is a multiple of y).
x = ny/(x-1)...now it not necessary that x is a multiple of y. Insufficient.
Thus, A
I hope it helps
Amit
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beeparoo
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I feel this part warrants additional explanation. For me, at least!erjamit wrote:x = ny/(x-1)...now it not necessary that x is a multiple of y. Insufficient.
I got to this point as well, but then considered that
n/(x - 1) can be considered a constant for 'y'.
In this case, I considered x to be a multiple of y. Ack! What is wrong with my conclusion?
n/(x - 1) can be considered a constant for 'y'.
ok look...x and y are integers as given by the stem and we are required to find whether x is a multiple of y.
both n and x-1 are integers, but is it necessary that n/(x-1) is also an integer...it can be it cant be...
I hope you are getting my point...
btw DS is my weak link...n m tryin to strengthen it...
Amit
ok look...x and y are integers as given by the stem and we are required to find whether x is a multiple of y.
both n and x-1 are integers, but is it necessary that n/(x-1) is also an integer...it can be it cant be...
I hope you are getting my point...
btw DS is my weak link...n m tryin to strengthen it...
Amit
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Ian Stewart
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Well, I look at the statment y is a divisor of x(x-1), and while there could be many possibilities here, one possibility is certainly that y = x-1. And if x > 2, x is not divisible by x-1; the remainder would always be 1 in that case. Choose any x > 2, let y = x-1, and you'll see why the information is insufficient.beeparoo wrote:I feel this part warrants additional explanation. For me, at least!erjamit wrote:x = ny/(x-1)...now it not necessary that x is a multiple of y. Insufficient.
I got to this point as well, but then considered that
n/(x - 1) can be considered a constant for 'y'.
In this case, I considered x to be a multiple of y. Ack! What is wrong with my conclusion?
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com
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