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when n is devided by 4, the remiander is 3. the remainder [#permalink ]
05 Oct 2007, 14:07

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when n is devided by 4, the remiander is 3. the remainder when 2n is devided by 4 is

a] 1

b] 2

c] 3

d] 6

e] 4

I am sort of on the right track here, but cant quite understand the last step. Ill post the OA in a bit. Oh, post your explanations as well

VP

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n/4 = y & remiander(3)

This can be expressed as:

4*y+3 = n

and

2*n = 2*(4*y+3) = 8*y+6

Easy to test ---> assume y=2

See bluebird's post

Last edited by

KillerSquirrel on 05 Oct 2007, 14:54, edited 1 time in total.

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I'm getting B....
n/4 = Q+3
Therefore, n=7,11,15,19,etc.
Using these values, 2n = 14,22,30,38,etc.
each of these values divided by 4 leaves a remainder of 2
Answer: B

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Re: PS: Remainder question [#permalink ]
05 Oct 2007, 14:43

pmenon wrote:

when n is devided by 4, the remiander is 3. the remainder when 2n is devided by 4 is

a] 1

b] 2

c] 3

d] 6

e] 4

I am sort of on the right track here, but cant quite understand the last step. Ill post the OA in a bit. Oh, post your explanations as well

B,

remainder is also multiplied by 2, so 6/4=1 plus remainder 2/4.

EDITTED*

Last edited by

IrinaOK on 05 Oct 2007, 16:10, edited 1 time in total.

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Bluebird wrote:

I'm getting B.... n/4 = Q+3 Therefore, n=7,11,15,19,etc. Using these values, 2n = 14,22,30,38,etc. each of these values divided by 4 leaves a remainder of 2 Answer: B

Yes you are correct !

the answer is (B)

VP

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Re: PS: Remainder question [#permalink ]
05 Oct 2007, 15:02

pmenon wrote:

when n is devided by 4, the remiander is 3. the remainder when 2n is devided by 4 is

a] 1

b] 2

c] 3

d] 6

e] 4

I am sort of on the right track here, but cant quite understand the last step. Ill post the OA in a bit. Oh, post your explanations as well

the best strategy to apply is picking numbers to save time;

7 fine remainder 3, ----> 14 remainder is 2

15 fine remainder 3, ----> 30 remainder is 2

19 fine remainder 3, -----> 38 remainder is 2

so B

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OA is B

I was approaching the question using formulas, but got stuck at this point:

n=4q+3

2n=8q+6

from here, without picking numbers, how do you figure out that the remainder is 2 ?

VP

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pmenon wrote:

OA is B

I was approaching the question using formulas, but got stuck at this point:

n=4q+3

2n=8q+6

from here, without picking numbers, how do you figure out that the remainder is 2 ?

i would not even attempt it with formulaes. now try to divide the final equation by four. u will not have chance to determine it then.

better use picking numbers as u save time for other questions