number property q.

This topic has expert replies
Junior | Next Rank: 30 Posts
Posts: 18
Joined: 20 Jun 2009
Thanked: 1 times
GMAT Score:720

number property q.

by godemol » Sun Aug 09, 2009 10:32 pm
If 3x + 7y = 8x − 18y and y > 7, then which of the following must be true?
a. x <7/5
b. x < 5
c. x > 18
d. x < 35
e. x > 36

The correct answer is c. I get to the point where x>35. Now, how is it that x>18 is a must? If x>35, shouldn't x be anything but smaller than 35, which would make "e" a correct choice? Thanks guys.

Legendary Member
Posts: 752
Joined: 17 May 2009
Location: Tokyo
Thanked: 81 times
GMAT Score:680

by tohellandback » Sun Aug 09, 2009 11:04 pm
X=5Y
since Y>7
X>35
from this you cannot tell that X>36
X can also be 35<X<36
but you can definitely say that X>18

so C
The powers of two are bloody impolite!!

Junior | Next Rank: 30 Posts
Posts: 18
Joined: 20 Jun 2009
Thanked: 1 times
GMAT Score:720

thanks for ur response

by godemol » Sun Aug 09, 2009 11:15 pm
From the question stem, I understand x>35. So, if x>18, choices like 19 and 20 doesn't even fall under x>35, but x values that are greater than 36 do fall under the condition x>35. I think I'm misunderstanding some basic concept here. Please clarify. Thanks.

Legendary Member
Posts: 752
Joined: 17 May 2009
Location: Tokyo
Thanked: 81 times
GMAT Score:680

Re: thanks for ur response

by tohellandback » Sun Aug 09, 2009 11:18 pm
godemol wrote:From the question stem, I understand x>35. So, if x>18, choices like 19 and 20 doesn't even fall under x>35, but x values that are greater than 36 do fall under the condition x>35. I think I'm misunderstanding some basic concept here. Please clarify. Thanks.
X>35
X can be 35.5,35.6... or 36, 36.2,455,1000
so X may or may not be >36

but whatever be the value of X, it will always be >18
so C is the best answer.
The powers of two are bloody impolite!!