Is x < y ?
STATEMENT 1:
10x > 10y
STATEMENT 2:
x + ab > y + ba
[spoiler]
OA: D. Can we actually say that St 1 will be sufficient on its own, cos after dividing by 10 we get x < y. Now dont we need to know the sign of x and y to say which is greater? [/spoiler]
X greater than Y - Doubt in sign
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By dividingrahulvsd wrote:Is x < y ?
STATEMENT 1:
10x > 10y
STATEMENT 2:
x + ab > y + ba
[spoiler]
OA: D. Can we actually say that St 1 will be sufficient on its own, cos after dividing by 10 we get x < y. Now dont we need to know the sign of x and y to say which is greater? [/spoiler]
10x > 10y by 10 on both sides you get
x > y
and NOT
y < x.
The sign of the inequality reverses only when you multiply or divide both sides of the inequality by a negative number. If you multiply or divide both sides by a positive number (such as 10), the sign of the inequality does not change.
Take the example of
3 > 2
If we divide by 10 on both sides, we get
0.3 > 0.2
which is true. The sign of the inequality does not change,
If we divide by -10 on both the sides, we get
-0.3 < -0.2
The sign of the inequality reverses.
This is a very important concept and I hope you've understood.
Statement(1) answers the question with a 'NO', so does Statement (2).
Aneesh Bangia
GMAT Math Coach
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GMAT Math Coach
[email protected]
GMATPad:
Facebook Page: https://www.facebook.com/GMATPad