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DS: The product of positive integers m and n is 36. What is

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by dvinoth86 » Sat Jan 21, 2012 4:59 am
The product of positive integers m and n is 36. What is the value of m + n?

(1) m is evenly divisible by 9.

(2) n is evenly divisible by 2.

what does evenly divisible mean? does is mean that the quotient is even number?
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Source: — Data Sufficiency |

by Brent@GMATPrepNow » Sat Jan 21, 2012 6:08 am
dvinoth86 wrote:The product of positive integers m and n is 36. What is the value of m + n?

(1) m is evenly divisible by 9.

(2) n is evenly divisible by 2.

what does evenly divisible mean? does is mean that the quotient is even number?
Don't worry about the "evenly" part.
"Evenly divisible" is the same a "divisible."

Here's one approach:
Since there aren't many cases in which mn=36, a quick approach might be to list the possibilities. I'll list each case in the form (m,n)
case a) (1,36)
case b) (2,18)
case c) (3,12)
case d) (4,9)
case e) (6,6)
case f) (9,4)
case g) (12,3)
case h) (18,2)
case i) (36,1)

Statement 1: m is divisible by 9.
This means we could have case f, h or i
case f --> sum = 37
case h --> sum = 20
Two conflicting answers to the target question means statement 1 is NOT SUFFICIENT

Statement 2: n is divisible by 2.
This means we could have case a, b, c, e, f, or h
case a --> sum = 13
case b --> sum = 20
Two conflicting answers to the target question means statement 2 is NOT SUFFICIENT

Statements 1 & 2 :
Statement 1 tells us we could have case f, h or i
Statement 2 tells us we could have case a, b, c, e, f, or h
So, we now know that we could have case f, or h
case f --> sum = 37
case h --> sum = 20
Two conflicting answers to the target question means statements 1 & 2 combined is NOT SUFFICIENT

Answer = E

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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