BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

GMATPrep Q

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Quantitative Reasoning |
Legendary Member
Posts: 829
Joined: Mon Jul 07, 2008 10:09 pm
Location: INDIA
Thanked: 84 times
Followed by:3 members

Re: GMATPrep Q

by sudhir3127 » Sat Aug 23, 2008 9:47 pm
smehmood wrote:What is the solution to the attached problems?
Thanks
M
its C

plug in the values and it will be cake walk...

Assume X=2 and Y =2

1. sqrt ( x+y)/2x
sqrt (4)/4 = 2/4 = 1/2........................................1

2. (rt x+ rt y)/x+y
(rt2 + rt 2)/4
2rt2/4 = rt2/2 > 1/2...................................................2


3. (sqrtx - rt y)/x+y = 0....................................3

hence C

.Hope it helps..
Top
Junior | Next Rank: 30 Posts
Posts: 29
Joined: Fri Jul 04, 2008 6:57 pm
Thanked: 1 times

by kv_ajay » Sun Aug 24, 2008 12:02 am
Sudhir,

You got the correct answer but i think there are various opportunities to plug in numbers and too much work.

Explanation from my point would be
Root (X) + Root (Y) => Root (X+Y)
e.g. X= 4, Y = 16 then 2+4 > 4.47

so Root (X) + Root (Y)
---------------------
Root (X+Y) Root (X+Y)

So 1/Root(X+Y) is multiplied by integer > 1 so it will always be greater than 1/(Root X+Y)
Top
Senior | Next Rank: 100 Posts
Posts: 54
Joined: Sat May 10, 2008 1:48 pm

by smehmood » Sun Aug 24, 2008 8:15 am
So, should we plug-in numbers in these type of questions?
I plug in numbers and I was getting both I and II greater then the number in question.

Ajay, you did not explain how you will compare x+y (denominator is II) with 2x (denominator in I)?

Thanks
M
Top
Junior | Next Rank: 30 Posts
Posts: 25
Joined: Tue Jul 01, 2008 11:54 am
Location: San Diego

by somail » Tue Aug 26, 2008 12:28 pm
Plugging numbers in is okay, but you need to be carefull. The question says "must be greater than" meaning in all situations.

Lets say we pick x=4 and y=12

for I we get:

sqrt(16)/8 = 1/2 which is greater

but if we were to use x=12 and y=4 we get:

sqrt(16)/24 = 1/6 which is less.

So in this situation you can pick numbers, but just be extra careful to think about all possibilities.
Top
Post new topic Post Reply
• Page 1 of 1