re: Math Experts: GMAT Help

I used Target Test Prep for quant. Can't recommend that company enough. I was mid 600's and they got me over the final hump to a 700.

Yeah, I think that's how they're trying to trip you up. You don't have enough information to solve for m and n, but that doesn't matter since that isn't what the question asked.

I've never taken the GMAT, so take this with a grain of salt. Just make sure you're answering the question that they are asking. Seems obvious, but it's an easy mistake to make.

C

Always go with C

quote:

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Does 2m - 3n = 0?

1) m /= 0
2) 6m = 9n

There are then 5 options of:

A. Equation 1 alone is sufficient
B. Equation 2 alone is sufficient
C. Both equations are sufficient alone
D. Equations are sufficient but only together
E. Neither equation is sufficient, even if they're togethe

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The answer to this is D and heres why. 2m-3n "could' equal zero but you cant say that it "does" equal 0 by equation 1 alone. If 6m=9n you can solve for the value of n as it relates to m and that would be n=6/9m or n=2/3m in simplest form. Therefore if n=2/3m and we already know that m=0 then n also=0. Y

You need both equations to have sufficient data to determine that yes it does indeed equal 0. Either equation alone allows for the possibility that they equal 0 but both together are required to prove it with certainty.

quote:

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Does 2m - 3n = 0?

1) m /= 0
2) 6m = 9n

---

Here I will throw a monkey wrench into the equation. Is there sufficient evidence that m=/=0, and therefore n=/=0? In pure mathematics terms this is referred to as the null solution.

I would argue that because it's necessary to establish that the null solution is not viable that both are required to establish 2m-3n=0.

My answer would have been D.

I am sure GMAT will disagree though.

quote:

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The answer to this is D and heres why. 2m-3n "could' equal zero but you cant say that it "does" equal 0 by equation 1 alone. If 6m=9n you can solve for the value of n as it relates to m and that would be n=6/9m or n=2/3m in simplest form. Therefore if n=2/3m and we already know that m=0 then n also=0. Y

You need both equations to have sufficient data to determine that yes it does indeed equal 0. Either equation alone allows for the possibility that they equal 0 but both together are required to prove it with certainty.

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Said much better than I did.

You could actually draw the solution to this as a line on a graph. If you put n as the y-axis and m as the x axis, the line would pass through the origin (0,0) and would continue with a slope of 2/3 forever in both directions. There are an infinite number of m,n combinations, but these values don't matter. The answer is B.

quote:

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quote:
Does 2m - 3n = 0?

1) m /= 0
2) 6m = 9n

There are then 5 options of:

A. Equation 1 alone is sufficient
B. Equation 2 alone is sufficient
C. Both equations are sufficient alone
D. Equations are sufficient but only together
E. Neither equation is sufficient, even if they're togethe



The answer to this is D and heres why. 2m-3n "could' equal zero but you cant say that it "does" equal 0 by equation 1 alone. If 6m=9n you can solve for the value of n as it relates to m and that would be n=6/9m or n=2/3m in simplest form. Therefore if n=2/3m and we already know that m=0 then n also=0. Y

You need both equations to have sufficient data to determine that yes it does indeed equal 0. Either equation alone allows for the possibility that they equal 0 but both together are required to prove it with certainty.

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Dude, if 6m = 9n, then 6m - 9n = 0, and dividing both sides by 3 gives 2m - 3n = 0, which is the original equation. So the answer is (B).

But by tying that equation to the problem and saying that it is now part of the system of equations, you have sufficient evidence to prove that the equation is true by solving as you would by replacing n in terms of m. That equation by itself is sufficient.

n=(6/9)m

Therefore

2m- 3*(6/9)m= 2m- (18/9)m= 2m-2m=0.


For those saying you must also know m/=0, why? It's not necessary. In simple terms of variables you can reduce it to show an argument minus itself is 0. So the one additional equation is sufficient.

Scored a 650 a few years ago.

Sufficient means that it is enough to answer the question. And 2 has enough information to answer the question.

D was always the trickiest answer for me because without fully working out a problem it would seem like 2 would be sufficient but it was definitely solvable when using 1 as well.