Is the number x between 0.1 and 1.0?
(1) 420x is less than 168.
(2) 650x is greater than 130.
OAC
Is the number x between 0.1 and 1.0?
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gmat_winter wrote:Is the number x between 0.1 and 1.0?
(1) 420x is less than 168.
(2) 650x is greater than 130.
OAC
Target question: Is x between 0.1 and 1.0?
Statement 1: 420x is less than 168.
So, 420x < 168
Divide both sides by 420 to get: x < 168/420
Simplify to get: x < 0.4
There are several values of x that satisfy this condition. Here are two:
Case a: x = 0.2, in which case x IS between 0.1 and 1
Case b: x = -5, in which case x is NOT between 0.1 and 1
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: 650x is greater than 130.
So, 650x < 130
Divide both sides by 650 to get: x > 130/650
Simplify to get: x > 0.2
There are several values of x that satisfy this condition. Here are two:
Case a: x = 0.3, in which case x IS between 0.1 and 1
Case b: x = 5, in which case x is NOT between 0.1 and 1
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined
Statement 1 says that x < 0.4
Statement 2 says that x > 0.2. In other words, 0.2 < x
Combine to get 0.2 < x < 0.4
If x is between 0.2 and 0.4, then we can be certain that x is between 0.1 and 1
Since we can answer the target question with certainty, the combined statements are SUFFICIENT
Answer = C
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Brent
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Hi gmat_winter,
In this DS prompt, you can actually avoid almost all of the "math" entirely. The 'design' of the prompt rewards Test Takers with 'pattern-matching' ability, and a variation on TESTing VALUES will work nicely here.
We're asked if X is between 0.1 and 1.0. This is a YES/NO question.
Fact 1: 420X is less than 168.
420X < 168
X < 168/420
168/420 is clearly a POSITIVE FRACTION that is bigger than .1 (10% of 420 = 42, so 42/420 would be .1)
IF X is close to 168/420, then the answer to the question is YES
If X is 0, then the answer to the question is NO
Fact 1 is INSUFFICIENT
Fact 2: 650X is greater than 130
650X > 130
X > 130/650
130/650 is clearly a POSITIVE FRACTION that is bigger than .1 (since 65/650 = .1).
IF X is close to 130/650, then the answer to the question is YES
If X is 1, then the answer to the question is NO
Fact 2 is INSUFFICIENT
Combined, we know that....
168/420 > X > 130/650
X is clearly a POSITIVE FRACTION that is greater than .1 (since 65/650 = .1)
The answer to the question is ALWAYS YES.
Combined, SUFFICIENT
Final Answer: C
GMAT assassins aren't born, they're made,
Rich
In this DS prompt, you can actually avoid almost all of the "math" entirely. The 'design' of the prompt rewards Test Takers with 'pattern-matching' ability, and a variation on TESTing VALUES will work nicely here.
We're asked if X is between 0.1 and 1.0. This is a YES/NO question.
Fact 1: 420X is less than 168.
420X < 168
X < 168/420
168/420 is clearly a POSITIVE FRACTION that is bigger than .1 (10% of 420 = 42, so 42/420 would be .1)
IF X is close to 168/420, then the answer to the question is YES
If X is 0, then the answer to the question is NO
Fact 1 is INSUFFICIENT
Fact 2: 650X is greater than 130
650X > 130
X > 130/650
130/650 is clearly a POSITIVE FRACTION that is bigger than .1 (since 65/650 = .1).
IF X is close to 130/650, then the answer to the question is YES
If X is 1, then the answer to the question is NO
Fact 2 is INSUFFICIENT
Combined, we know that....
168/420 > X > 130/650
X is clearly a POSITIVE FRACTION that is greater than .1 (since 65/650 = .1)
The answer to the question is ALWAYS YES.
Combined, SUFFICIENT
Final Answer: C
GMAT assassins aren't born, they're made,
Rich