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500 DS

This topic has 1 member reply
dunkin77 Master | Next Rank: 500 Posts Default Avatar
Joined
01 Apr 2007
Posted:
269 messages

500 DS

Post Sun Apr 01, 2007 1:35 pm
Hello,

The answer is B) but I though the answer was C)... Can anypne explain??


21. If K is a positive integer less than 10 and N = 4,321 + K, what is the value of K?
(1) N is divisible by 3.
(2) N is divisible by 7.

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Prasanna Master | Next Rank: 500 Posts
Joined
26 Feb 2007
Posted:
418 messages
Upvotes:
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Post Sun Apr 01, 2007 4:55 pm
dunkin77 wrote:
Hello,

The answer is B) but I though the answer was C)... Can anypne explain??


21. If K is a positive integer less than 10 and N = 4,321 + K, what is the value of K?
(1) N is divisible by 3.
(2) N is divisible by 7.
---------------------------------------------------------------

When you consider (1), N could be 4323, 4326 and 4329. This option is ruled out since it does not give a definite value

When you consider (2), N could only be 4326. The information in this option is sufficient to determine N. Hence the answer is (B).

This is a trap in many DS questions. We should train our minds to not get tempted to use both the options unless either one is not SUFFICIENT. I have made many such mistakes in my practice.

Prasanna

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