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Need help determining answer

by jowe125 » Mon Dec 19, 2011 1:13 pm
The question reads:

If K is a positive integer less than 10 and N=4321 +K, what is the value of K?

1. N is divisible by 3
2. N is divisible by 7

I can determine that 1 is insufficient because k could be 2, 5 or 8. I cannot determine whether 2 is sufficient or not. The divisibility rule for 7 isn't as straightforward and need another approach to get to the right answer which is B.

Can someone help please???

Thanks.
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by Mdewan » Mon Dec 19, 2011 1:24 pm
Ans: B

Statement 1: Gives you 3 options - 2, 5 & 8

Statement 2: N is divisible by 7
When you divide 4321 by 7, you get the remainder 2, you need to add 5 to 4321, to have the number divisible by 7.
Since K<10
K can only be 5 in this case

Hence B is sufficient
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by neelgandham » Mon Dec 19, 2011 2:59 pm
jowe125 wrote:The question reads:

If K is a positive integer less than 10 and N=4321 +K, what is the value of K?

1. N is divisible by 3
2. N is divisible by 7

I can determine that 1 is insufficient because k could be 2, 5 or 8. I cannot determine whether 2 is sufficient or not. The divisibility rule for 7 isn't as straightforward and need another approach to get to the right answer which is B.
Can someone help please???
Thanks.
It is easier to divide the number 4321 by 7, than to learn by heart. When you divide 4321 by 7, you are left with 2 as a remainder. For 4321+k to be divisible by 7, 2+k should be divisible by 7. For 2+K to be divisible by 7, K should be 5 or 12 or 19..But k <10. So, the value of K is 5. If you still insist on the divisibility rule of 7. Here it is.

https://www.youtube.com/watch?v=LPgAK7whEuw
Anil Gandham
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