Remainder

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Remainder

by cuty » Thu Mar 03, 2011 7:10 am
2.What is the remainder when the positive integer X is divided by 3?
a) When X is divided by 6 the remainder is 2
b) When X is divided by 15 the remainder is 2







answer is D ..can ny body explain why??

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by manpsingh87 » Thu Mar 03, 2011 7:15 am
cuty wrote:2.What is the remainder when the positive integer X is divided by 3?
a) When X is divided by 6 the remainder is 2
b) When X is divided by 15 the remainder is 2







answer is D ..can ny body explain why??
a) when x is divided by 6 remainder is 2 therefore x can be written as 6k+2;

when this number is divided by 3 it will give a remainder of 2 hence a) is sufficient.

B) similarly for b x will be of the type 15K+2;
when this number is divided by 3 it will give a remainder of 2 hence b) is sufficient.

hence both a and b alone are sufficient to answer the question..!!!
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by Night reader » Thu Mar 03, 2011 7:20 am
Please move this question to DS forum :)
x/3 = i {i is integer} + r/3 where r is remainder, find r-?
st(1) x/6=i+2/6, the number can be divided by 6 if it can be divided by 3 and 2 --> multiply x by 2 and get x/3=2i +2/3, hence r=4 Sufficient
st(2) x/15=i + 2/15, the number can be divided by 15 if it can be divided by 3 and 5 --> multiply x by 5 and get x/3=5i +2/3, hence r=4 Sufficient

answer must be D
cuty wrote:2.What is the remainder when the positive integer X is divided by 3?
a) When X is divided by 6 the remainder is 2
b) When X is divided by 15 the remainder is 2







answer is D ..can ny body explain why??
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by Rich@VeritasPrep » Thu Mar 03, 2011 7:46 am
If you're unsure of the algebraic properties, this question is a very good candidate for testing numbers. In fact, that's probably the fastest way to go about this problem.

The question is "What is the remainder when the positive integer X is divided by 3?"

Let's look at the statements:

a) When X is divided by 6 the remainder is 2

Pick numbers: X = 2, 8, 14, 20,...

No matter which X you pick, the answer to the question will always be 2. SUFFICIENT


b) When X is divided by 15 the remainder is 2

X = 2, 17, 32, ...

Same thing. No matter which X you pick, the answer to the question will always be 2. SUFFICIENT
Rich Zwelling
GMAT Instructor, Veritas Prep