Since denominator is negative, we know the answer must be negative. Are there other secrets to doing this faster?
1/(0.75 - 1) =
A) -4
B) -0.25
C) 0.25
D) 0.75
E) 4
A
Simple fraction
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Yes, you are correct; since the numerator is positive and the denominator is negative, the result is negative, thus answer could be between option A and B.AbeNeedsAnswers wrote:Since denominator is negative, we know the answer must be negative. Are there other secrets to doing this faster?
1/(0.75 - 1) =
A) -4
B) -0.25
C) 0.25
D) 0.75
E) 4
A
There is no secret to doing this faster. One must deal with a decimal and a fraction.
Mentally, you can do this one since you wish to have the most efficient approach.
0.75 is a popular and most commonly used decimal, it is a 3/4th of a number.
Thus (0.75 - 1) is a negative of 1/4th of the number. Or, (0.75 - 1) = -1/4
Once you flip -1/4, you get -4, the correct answer.
The correct answer: A
Hope this helps!
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Useful fraction property: 1/(a/b) = b/aAbeNeedsAnswers wrote:Since denominator is negative, we know the answer must be negative. Are there other secrets to doing this faster?
1/(0.75 - 1) =
A) -4
B) -0.25
C) 0.25
D) 0.75
E) 4
A
For example: 1/(2/3) = 3/2
And 1/(19/7) = 7/19
So, 1/(0.75 - 1) = 1/(-0.25) = 1/(-1/4) = -4
Alternatively, 1/(0.75 - 1) = 1/(3/4 - 4/4) = 1/(-1/4) = -4
Cheers,
Brent
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Hi AbeNeedsAnswers,
From a 'concept' standpoint, increasing or decreasing the denominator of a fraction will impact whether the fraction increases or decreases in value.
For example, if we're dealing with a positive fraction....
eg. 1/4
Decreasing the denominator makes the fraction BIGGER (e.g.. 1/3 is greater than 1/4)
Increasing the denominator makes the fraction SMALLER (e.g.. 1/5 is less than 1/4)
In this question, we're dealing with a positive numerator and a NEGATIVE denominator, so similar patterns will occur.
eg. 1/-3
As the denominator gets FARTHER from 0, the fraction gets CLOSER to 0 (-1/4 is closer to 0 than -1/3 is)
As the denominator gets CLOSER to 0, the fraction gets FARTHER from 0 (-1/2 is farther from 0 than -1/3 is)
In this question, since the denominator is - .25, that means the value of 1/(-.25) is FARTHER from 0 than 1/-1 is. There's only one answer that fits that pattern.
Final Answer: A
GMAT assassins aren't born, they're made,
Rich
From a 'concept' standpoint, increasing or decreasing the denominator of a fraction will impact whether the fraction increases or decreases in value.
For example, if we're dealing with a positive fraction....
eg. 1/4
Decreasing the denominator makes the fraction BIGGER (e.g.. 1/3 is greater than 1/4)
Increasing the denominator makes the fraction SMALLER (e.g.. 1/5 is less than 1/4)
In this question, we're dealing with a positive numerator and a NEGATIVE denominator, so similar patterns will occur.
eg. 1/-3
As the denominator gets FARTHER from 0, the fraction gets CLOSER to 0 (-1/4 is closer to 0 than -1/3 is)
As the denominator gets CLOSER to 0, the fraction gets FARTHER from 0 (-1/2 is farther from 0 than -1/3 is)
In this question, since the denominator is - .25, that means the value of 1/(-.25) is FARTHER from 0 than 1/-1 is. There's only one answer that fits that pattern.
Final Answer: A
GMAT assassins aren't born, they're made,
Rich
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1/(.75 - 1) =>
1/(-.25) =>
-(1/.25) =>
-1/(1/4) =>
-4
I wouldn't worry about speed here since this is about as quick a GMAT problem as I can recall - is it from the OG?
1/(-.25) =>
-(1/.25) =>
-1/(1/4) =>
-4
I wouldn't worry about speed here since this is about as quick a GMAT problem as I can recall - is it from the OG?
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Useful fraction property: 1/(a/b) = b/aAbeNeedsAnswers wrote:Since denominator is negative, we know the answer must be negative. Are there other secrets to doing this faster?
1/(0.75 - 1) =
A) -4
B) -0.25
C) 0.25
D) 0.75
E) 4
A
For example: 1/(2/3) = 3/2
And 1/(19/7) = 7/19
So, 1/(0.75 - 1) = 1/(-0.25) = 1/(-1/4) = -4/1 = -4
Alternatively, 1/(0.75 - 1) = 1/(3/4 - 4/4) = 1/(-1/4) = -4
Cheers,
Brent
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We start by subtracting 1 from 0.75 in the denominator of 1/(0.75 - 1). This yields:AbeNeedsAnswers wrote:Since denominator is negative, we know the answer must be negative. Are there other secrets to doing this faster?
1/(0.75 - 1) =
A) -4
B) -0.25
C) 0.25
D) 0.75
E) 4
1/(-0.25)
Since 0.25 = 1/4, we see that -0.25 = -1/4. This now gives us:
1/(-1/4) = 1 x -4 = -4
Answer: A
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