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by dddanny2006 » Fri Nov 15, 2013 9:18 am
Is mn divisible by 40?
(1)m is divisible by 40
(2)n is divisible by 4




Can anyone help me with this question via the Prime boxes method.

Thanks
Last edited by dddanny2006 on Fri Nov 15, 2013 9:27 am, edited 1 time in total.
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Source: — Data Sufficiency |
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by theCodeToGMAT » Fri Nov 15, 2013 9:22 am
dddanny2006, one question per thread please
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by dddanny2006 » Fri Nov 15, 2013 9:38 am
Done
theCodeToGMAT wrote:dddanny2006, one question per thread please
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by theCodeToGMAT » Fri Nov 15, 2013 9:45 am
To find: mn divisible by 40 ==> mn/4*2*5

So we need atleast single instance of "4", "2" & "5"

Statement 1:
m/40 ---> we got one instance of "4", "2" & "5"
Say m is 40
So, (40)(n)/40 ==> YES
But, "n" can be non-integer.
INSUFFICIENT

Statement 2:
n/4 --> we only got "4"
We don't know whether "m" is divisible by 10 or not.
Say n = 4, m = 15
(15)(4)/40 ==> NO
Say n = 4, m = 10
(4)(10)/40 ==> YES
INSUFFICIENT

Combining...
m/40 & n/4
We got "4", "2" & "5" also "n" is INTEGER.
SUFFICIENT

Answer [spoiler]{C}[/spoiler]
Last edited by theCodeToGMAT on Fri Nov 15, 2013 10:04 am, edited 1 time in total.
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by dddanny2006 » Fri Nov 15, 2013 9:53 am
I'd say statement 1 is insufficient because n may be an integer,say 0.5?
theCodeToGMAT wrote:To find: mn divisible by 40 ==> mn/4*2*5

So we need atleast single instance of "4", "2" & "5"

Statement 1:
m/40 ---> we got one instance of "4", "2" & "5"
Say m is 40
So, (40)(n)/40 ==> YES
SUFFICIENT

Statement 2:
n/4 --> we only got "4"
We don't know whether "m" is divisible by 10 or not.
Say n = 4, m = 15
(15)(4)/40 ==> NO
Say n = 4, m = 10
(4)(10)/40 ==> YES
INSUFFICIENT

Is it Answer [spoiler]{A}[/spoiler]???
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by dddanny2006 » Fri Nov 15, 2013 9:56 am
I'd say statement 1 is insufficient because n could be an integer,say 0.5
theCodeToGMAT wrote:To find: mn divisible by 40 ==> mn/4*2*5

So we need atleast single instance of "4", "2" & "5"

Statement 1:
m/40 ---> we got one instance of "4", "2" & "5"
Say m is 40
So, (40)(n)/40 ==> YES
SUFFICIENT

Statement 2:
n/4 --> we only got "4"
We don't know whether "m" is divisible by 10 or not.
Say n = 4, m = 15
(15)(4)/40 ==> NO
Say n = 4, m = 10
(4)(10)/40 ==> YES
INSUFFICIENT

Is it Answer [spoiler]{A}[/spoiler]???
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by theCodeToGMAT » Fri Nov 15, 2013 10:00 am
yeah correct, I cannot assume that "n" is Integer; solution modified.
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