MathRevolution wrote:

Is xy < 10?

1) x < 2

2) y < 5

Target question: Is xy< 10? Statement 1: x < 2 Since there's no information about y, this statement is not sufficient.

However, if we're not certain about this insufficiency, we can TEST some values.

There are several values of x and y that satisfy statement 1. Here are two:

Case a: x = 1 and y = 1, which means xy = (1)(1) = 1. So,

xy < 10Case b: x = 1 and y = 20, which means xy = (1)(20) = 1. So,

xy > 10Since we cannot answer the

target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: y < 5Since there's no information about x, this statement is not sufficient.

Let's test some values (for "fun")

Case a: x = 1 and y = 1, which means xy = (1)(1) = 1. So,

xy < 10Case b: x = 10 and y = 2, which means xy = (10)(2) = 20. So,

xy > 10Since we cannot answer the

target question with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined There are still several values of x and y that satisfy BOTH statements and yield contradictory answers to the

target question. Here are two:

Case a: x = 1 and y = 1, which means xy = (1)(1) = 1. So,

xy < 10Case b: x = -5 and y = -6, which means xy = (-5)(-6) = 30. So,

xy > 10Since we cannot answer the

target question with certainty, the combined statements are NOT SUFFICIENT

Answer:

Cheers,

Brent

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Brent Hanneson – Founder of gmatprepnow.com