Kaplan Test Q

[vittalgmat]

What is the value of ab ?

1. a/b = 2
2. a + b = 6

[spoiler]OA is C but I get E. Also the OA explains stmt 1 can be transformed
as a=2b. I dont agree, coz we dont know whether a, b are not equal to 0.
So we cant multiply or divide by either a or b.
Am I missing something?? [/spoiler]

Source: Kaplan CAT

[vishubn]

A) it gives u thr ration of a/b=2/1

so we know the ratio.... Infuss

B) a+b= can be anything.... INsuff

a has to be multiple of of b

1+5,2+4,3+3,4+2,5+1...

a=4,b=2 is the only value which suits

OA C

BUT!!!!! i am not totally happy !! coz... i am on impression a and b are integers ! and posotive!!

can even prove me wrong ?? please.....

[vittalgmat]

Vishu,
I dont think we can assume that a, b are integers.
Also I dont think we can assume a, b are non-zero.

so a, b can be any numbers (0, +ve int, - ve int, irrational nos,
+ve/-ve fractions, )..

In that case I get E.

Am I right ??

thanks

[vishubn]

Vishu,
I dont think we can assume that a, b are integers.
Also I dont think we can assume a, b are non-zero.

so a, b can be any numbers (0, +ve int, - ve int, irrational nos,
+ve/-ve fractions, )..

In that case I get E.

Am I right ??

thanks

hi vittal.... yaa on the assumption of ur line! i would go with E as well !! !!

vishu

[Brent@GMATPrepNow]

What is the value of ab ?

1. a/b = 2
2. a + b = 6

(1) if a/b = 2 then a = 2b

(2) using the result from (1) replace a with 2b to get 2b + b = 6, which means that b=2

From here we know that a=4

So, ab = 8

[cramya]

[spoiler]OA is C but I get E. Also the OA explains stmt 1 can be transformed
as a=2b. I dont agree, coz we dont know whether a, b are not equal to 0.
So we cant multiply or divide by either a or b.
Am I missing something?? [/spoiler]

Vittal,

I
a,b both have to be be non zero for a/b to equal 2. At this point yes we dont know if its intgers or not

a=4 b=2 a/b=2 or a = 2b (this is equality and not inequality like <,<=,>,>= where we CANNOT cross multiply without knowing the signs of a and b )

a=7 b= 3.5 a/b = 2

INSUFF

II

a+b = 6 There ar many initgers/decimlas that can make this statement true

INSUFF


COMBINE STMT I AND II

a = 2b

a+b = 6
2b+b= 6
b=2

a = 4

ab = 8

Choose C)

Let me know if u still feel otherwise.

Regards,
Cramya

[vittalgmat]

Thanks Everyone for the answers. You guys are right..
a/b =2 implies that both a and b are non-zero. hence one can
write a = 2b.
Now C is right.

best regards