Is xy<10?

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Is xy<10?

by Max@Math Revolution » Sun Jul 31, 2016 7:55 am
Is xy<10?
1) x<5
2) y<2

*An anwer will be posted in 2 days.
Source: — Data Sufficiency |

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by Brent@GMATPrepNow » Tue Aug 02, 2016 5:35 am
Max@Math Revolution wrote:Is xy < 10?

1) x < 5
2) y < 2
Target question: Is xy < 10?

Statement 1: x < 5
No information about y.
Statement 1 is NOT SUFFICIENT

Statement 2: y < 2
No information about x.
Statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined
There are several values of x and y that satisfy BOTH statements. Here are two:
Case a: x = 4 and y = 1, in which case xy = (4)(1) = 4, and 4 < 10
Case b: x = -4 and y = -3, in which case xy = (-4)(-3) = 12, and 12 > 10
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer = E

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Brent
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by Max@Math Revolution » Thu Aug 04, 2016 6:20 pm
There are 2 variables (x and y) and there is a high chance that C is the correct answer. Using con 1) and 2), the answer is yes when xy=1 and the answer is no when x=y=-5. Hence, the condition is not sufficient. So, the correct answer is E.