Of the following, which if closest to ?
(0.15*495)/9.97
(A) 7.5
(B) 15
(C) 75
(D) 150
(E) 750
These type of questions involve approximation of a certain kind. How do I ensure I pick the right answer?
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Approximation
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Since the answer choices are spread out, our calculations do not have to be very precise.RiyaR wrote:Of the following, which if closest to ?
(0.15*495)/9.97
(A) 7.5
(B) 15
(C) 75
(D) 150
(E) 750
Round 495 up to 500 and 9.97 up to 10, as follows:
(15/100 * 500)/10 = 75/10 = 7.5.
The correct answer is A.
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Followed here and elsewhere by over 1900 test-takers.
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As Mitch mentioned, the answer choices are spread out, so we can use some estimation. In fact, I'd say the answer choices a VERY SPREAD OUT, which means we can be SUPER lenient with our estimation.RiyaR wrote:Of the following, which if closest to ?
(0.15*495)/9.97
(A) 7.5
(B) 15
(C) 75
(D) 150
(E) 750
So, another way to tackle the question is to recognize that 0.15 is close to 1/7, 495 is close to 490, and 9.97 s close to 10.
So, we get: (1/7)(490)/10 = 70/10 = 7
Answer choice A is the only answer choice close to 7, so it must be the correct answer.
This strategy and others are covered in our free video, "General GMAT Math Strategies": https://www.gmatprepnow.com/module/gener ... es?id=1111
Cheers,
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Brent@GMATPrepNow wrote:As Mitch mentioned, the answer choices are spread out, so we can use some estimation. In fact, I'd say the answer choices a VERY SPREAD OUT, which means we can be SUPER lenient with our estimation.RiyaR wrote:Of the following, which if closest to ?
(0.15*495)/9.97
(A) 7.5
(B) 15
(C) 75
(D) 150
(E) 750
So, another way to tackle the question is to recognize that 0.15 is close to 1/7, 495 is close to 490, and 9.97 s close to 10.
So, we get: (1/7)(490)/10 = 70/10 = 7
Answer choice A is the only answer choice close to 7, so it must be the correct answer.
This strategy and others are covered in our free video, "General GMAT Math Strategies": https://www.gmatprepnow.com/module/gener ... es?id=1111
Cheers,
Brent
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The options are widely separated, therefore the approximation can be done quickly and easilyRiyaR wrote:Of the following, which if closest to ?
(0.15*495)/9.97
(A) 7.5
(B) 15
(C) 75
(D) 150
(E) 750
These type of questions involve approximation of a certain kind. How do I ensure I pick the right answer?
(0.15*495)/9.97 = (15/100) *500/10 = 7.5
Approximation of 9.97 = 10
Approximation of 495 = 500
Approximation of 0.15 = 15/100
Answer: Option A
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Hi RiyaR,
Each of the given explanations essentially explains the same thing, so I won't rehash any of that here.
I can tell you that the GMAT will ask you to perform at least 1 approximation during the Quant section (it's a built in "skill test" that is a part of every Test Taker's exam). Beyond that, you should be ready to use the answer choices to your advantage. When the answers are properly "spaced out", as they are in this prompt, you have an opportunity to save time by NOT performing the exact calculation that is given. Be on the lookout for these opportunities.
The exception to this rule is when the answer choices are "decimal shifted."
For example:
.02
.2
2
20
200
These types of questions are almost always based on PEMDAS rules, so you MUST perform the proper calculations, otherwise you'll be "off" by some factor of 10.
GMAT assassins aren't born, they're made,
Rich
Each of the given explanations essentially explains the same thing, so I won't rehash any of that here.
I can tell you that the GMAT will ask you to perform at least 1 approximation during the Quant section (it's a built in "skill test" that is a part of every Test Taker's exam). Beyond that, you should be ready to use the answer choices to your advantage. When the answers are properly "spaced out", as they are in this prompt, you have an opportunity to save time by NOT performing the exact calculation that is given. Be on the lookout for these opportunities.
The exception to this rule is when the answer choices are "decimal shifted."
For example:
.02
.2
2
20
200
These types of questions are almost always based on PEMDAS rules, so you MUST perform the proper calculations, otherwise you'll be "off" by some factor of 10.
GMAT assassins aren't born, they're made,
Rich
