integers

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integers

by yakiraz » Sun Jul 27, 2008 2:56 am
hi guys, hope you can help me with 2 questions:

A- In the fraction x/y, where x and y are positive integers, what is the value of y?

1) the least common denominator of x/y and 1/3 is 6
2) x=1


B- If w,x,y,z are integers such that w/x and y/z are integers. is w/x + y/z odd?

1)wx + yz is odd
2)wz + xy is odd

OA for the first question is E and for the second B

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by kris610 » Sun Jul 27, 2008 2:56 pm
1) A indicates y could be 2 or 6. INSUFFICIENT.
B does not help in any way to resolve y.
Put together, y could be 2 or 6. so E.

2) Divide the second expression by xz and you will get (w/x) + (y/z). Since, the expression given in B indicates it is odd, and the stem indicates that (w/x) and (y/z) are integers it must be true that (w/x) + (y/z) is an odd integer -- You divide an odd integer by another integer and the result is either an odd integer or a non-integer.

Hope this clarifies.

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by ildude02 » Sun Jul 27, 2008 3:49 pm
kris610 wrote:1) A indicates y could be 2 or 6. INSUFFICIENT.
B does not help in any way to resolve y.
Put together, y could be 2 or 6. so E.
Hope this clarifies.
Can you please clarify how you derived the values of Y from the LCM?

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Re: integers

by enniguy » Mon Jul 28, 2008 2:28 am
yakiraz wrote:hi guys, hope you can help me with 2 questions:

A- In the fraction x/y, where x and y are positive integers, what is the value of y?

1) the least common denominator of x/y and 1/3 is 6
2) x=1


B- If w,x,y,z are integers such that w/x and y/z are integers. is w/x + y/z odd?

1)wx + yz is odd
2)wz + xy is odd

OA for the first question is E and for the second B
--- A ---
Ans: E
In statement 1,
y can be either 6 or 2.

Calculate LCM of,
x/2 + 1/3 = z/6

Calculate LCM of,
x/6 + 1/3 = z/6

In both case we get the LCM of denominator to be 6.
so INSUFFICIENT

Statement 2 doesnt help much so INSUFFICIENT.