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dddanny2006: Master | Next Rank: 500 Posts; Posts: 209; Joined: Thu Jan 12, 2012 12:59 pm

by dddanny2006 » Tue Aug 27, 2013 4:50 am

Hello people,

Needed your opinion on this
Its a simple question.
If a>0,b>0 and 2c=sqrt(a/b) ,what is the value of b

1.a=8 and c=2
2.(c^2/a)=1/2 (Its c square by a equals half)

The answer is D

Now my question is what if they had not given a>0 and b>0

Does it impact the question?

Or does the answer remain the same in that case too??

Please share your opinion on this.

Thanks

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Source: Beat The GMAT — Data Sufficiency | Tue Aug 27, 2013 4:50 am

Jim@StratusPrep: MBA Admissions Consultant; Posts: 2279; Joined: Fri Nov 11, 2011 7:51 amFollowed by: 266 members; Location: New York; Thanked: 660 times; GMAT Score:770

by Jim@StratusPrep » Tue Aug 27, 2013 8:24 am

Wouldn't matter in the context of the GMAT because you can't take the sqrt of a negative number. That is all they are getting across.

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by [email protected] » Tue Aug 27, 2013 11:54 am

Hi dddanny2006,

I'm going to elaborate on what Jim offered regarding certain math subjects on the GMAT. The Quant section of the GMAT comes with many restrictions, which is why the questions are so specifically worded.

For example, a question that refers to x/y will also have to state that y CANNOT EQUAL 0, because dividing by 0 (otherwise known as "undefined numbers" or "infinities") is not a subject that's tested on the GMAT.

To be more specific, you will never be asked to do Calculus, Trigonometry, or Algebra II. In this question, you won't be asked to take the square root of a negative number because THAT is an Algebra II subject (so the limitations on a and b had to be included in the instructions).

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faraz_jeddah: Master | Next Rank: 500 Posts; Posts: 358; Joined: Thu Apr 18, 2013 9:46 amFollowed by: 7 members; Location: Jeddah, Saudi Arabia; Thanked: 42 times; GMAT Score:730

by faraz_jeddah » Wed Aug 28, 2013 6:41 am

[email protected] wrote:Hi dddanny2006,

I'm going to elaborate on what Jim offered regarding certain math subjects on the GMAT. The Quant section of the GMAT comes with many restrictions, which is why the questions are so specifically worded.

For example, a question that refers to x/y will also have to state that y CANNOT EQUAL 0, because dividing by 0 (otherwise known as "undefined numbers" or "infinities") is not a subject that's tested on the GMAT.

To be more specific, you will never be asked to do Calculus, Trigonometry, or Algebra II. In this question, you won't be asked to take the square root of a negative number because THAT is an Algebra II subject (so the limitations on a and b had to be included in the instructions).

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Rich

Thanks Rich for a detailed explanation.

There is another rule regarding square roots. Can you confirm the rule below

x^2 = 4
x can be 2 or -2

but if
x = sq.rt 4
then x can only be 2.

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by [email protected] » Wed Aug 28, 2013 12:16 pm

Hi faraz_jeddah,

You are correct. On the GMAT, if you start with....

x^2 = 25, then there are TWO answers: +5 and -5

But if you start with...

squareroot(25), then there is JUST ONE answer: +5

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