Cambridge tests - dont get tricked....

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Cambridge tests - dont get tricked....

by arora007 » Thu Jan 20, 2011 6:04 am
If y is a positive integer, what is the remainder when y is divided by 6?

1) The remainder is 1 when y-1 is divided by 6
2) The remainder is 0 when 3y is divided by 6


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OA A dont get tricked[/spoiler]
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by advita » Thu Jan 20, 2011 6:29 am
1.y-1=6k+1 ==> y=6k+2, reminder is always 2.
2. y=0 or 2 ... reminder =0 ,or 2.

so A.

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by Rahul@gurome » Thu Jan 20, 2011 7:24 am
arora007 wrote:If y is a positive integer, what is the remainder when y is divided by 6?

1) The remainder is 1 when y-1 is divided by 6
2) The remainder is 0 when 3y is divided by 6
Statement 1: Implies (y - 2) is divisible by 6. Hence y leaves a remainder of 1 when divided by 6.

Sufficient

Statement 2: 3y is divisible by 6. Now y may or may not be divisible by 6.

Not sufficient

The correct answer is A.

Note: If we know the remainder when a linear expression of some non-negative integer n is divided by a positive integer q, then we can always find the remainder when any other linear expression of n (including n itself) is divided by q. Thus if we know the remainder when (3n + 4) is divided by 5, we can determine the remainder when n or (2n + 1) or (10n - 3) or etc is divided by 5.

Thus just by reading the statement 1, we can confidently say it is sufficient.
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