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# Find a/b, if a and b have odd number of factors?

Author Message
Manager
Joined: 13 May 2017
Posts: 103
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Concentration: Accounting, Entrepreneurship
GMAT 1: 530 Q42 V22
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Find a/b, if a and b have odd number of factors?  [#permalink]

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11 Oct 2018, 01:00
1
4
00:00

Difficulty:

55% (hard)

Question Stats:

63% (02:20) correct 38% (01:54) wrong based on 40 sessions

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Find a/b, if a and b have odd number of factors?

(1) √b -√a = 2
(2) √a is even and has only 2 factors
Math Expert
Joined: 02 Aug 2009
Posts: 7334
Re: Find a/b, if a and b have odd number of factors?  [#permalink]

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11 Oct 2018, 07:31
3
Find a/b, if a and b have odd number of factors?

Odd number of factors means a and b are perfect squares.

(1) √b -√a = 2
Since a and b are squares, b=x^2 and a=y^2
So x-y=2..
But x and y can any values
Insufficient

(2) √a is even and has only 2 factors
2 factors means prime so √a=2..a=4
Insufficient

Combined
a=4 and b=(2+2)^2=16
a/b=4/16=1/4
Sufficient

C
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html
4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html

GMAT Expert

Re: Find a/b, if a and b have odd number of factors?   [#permalink] 11 Oct 2018, 07:31
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