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Number Properties :Chap 13:Pg 177: QR 2nd Edition Q 64

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netinetineti
 Post subject: Number Properties :Chap 13:Pg 177: QR 2nd Edition Q 64
 Post Posted: Sat Dec 03, 2011 10:20 pm 
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Hi,

Number Properties :Chap 13:Pg 177: Challenge Short Set - Number Properties: QR 2nd Edition Q 64:

If y is an integer, is y^3 divisible by 9?
(1) y is divisible by 4
(2) y is divisible by 6

Answer given is B.

Cant it be D?
Both (1) and (2) alone can be satisfied when y = 0.
And hence y^3 will be divisible by 9
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tim
 Post subject: Re: Number Properties :Chap 13:Pg 177: QR 2nd Edition Q 64
 Post Posted: Tue Dec 13, 2011 2:41 am 
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You seem to be confused as to how DS works. You can’t plug in one number, get one value, and conclude that you’ve got enough information to answer the question they ask. Yes, y^3 is divisible by 9 when y = 0, but you haven’t considered the infinite number of other possible values for y..

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Tim Sanders
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