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Subhajit007
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Kunal takes ‘a’ days to complete a work while Sandeep takes ‘b’ less d 10 May 2019, 02:07
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A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

95% (hard)

Question Stats:

24% (02:56) correct 76% (03:13) wrong based on 171 sessions

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Kunal takes ‘a’ days to complete a work while Sandeep takes ‘b’ less days than Kunal to complete the same work. Ravi takes ‘b’ more days than Kunal to complete the same work. Rahul takes ‘ab’ days to complete the work while Shyam takes ‘ab*ab’ days to complete it. Is the combined efficiency of Sandeep and Ravi together less than that of Rahul and Shyam together?

Statement I: b ≥ 1

Statement II: b ≤ 1
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A
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Noshad
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Kunal takes ‘a’ days to complete a work while Sandeep takes ‘b’ less d 12 May 2019, 09:01
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Hi Subhajit007
Can you provide the explanation ?
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MahmoudFawzy
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Kunal takes ‘a’ days to complete a work while Sandeep takes ‘b’ less d 12 May 2019, 10:47
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It is from Bank accountants' aptitude test.
I think it is too tough to be on GMAT

Explanation:
https://www.smartkeeda.com/Quantitative_Aptitude/Arithmetic/Data_Sufficiency_Quiz/newest/all/passage/Data_Sufficiency_Quiz_7/page/2
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Kunal takes ‘a’ days to complete a work while Sandeep takes ‘b’ less d 01 Jun 2019, 00:25
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I think the problem takes so much time to solve and less likely to appear similar problem in GMAT exam. Could you please mention the source from where it was taken ?
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Kunal takes ‘a’ days to complete a work while Sandeep takes ‘b’ less d 01 Jun 2019, 03:04
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gadde22
I think the problem takes so much time to solve and less likely to appear similar problem in GMAT exam. Could you please mention the source from where it was taken ?
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Hi gadde22
The source is mentioned in the last comment before yours.
It is not a GMAT question.
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BALAGURU
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Kunal takes ‘a’ days to complete a work while Sandeep takes ‘b’ less d 17 May 2020, 23:21
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Kunal takes ‘a’ days to complete a work while Sandeep takes ‘b’ less days than Kunal to complete the same work. Ravi takes ‘b’ more days than Kunal to complete the same work. Rahul takes ‘ab’ days to complete the work while Shyam takes ‘ab*ab’ days to complete it. Is the combined efficiency of Sandeep and Ravi together less than that of Rahul and Shyam together?

Sandeep and Ravi work / day together ==> 2a / (a^2 - b^2) ----- A
Rahul and Shyam work/day together ==> 1+ ab / (ab)^2 ----- B
A < B ?

1. b >=1
say a=2 , b=1
A ==> 2.2 /( 2^2 - 1) = 4/3 work / day
B ==> 2+1 / 4 = 3/ 4 work / day
therefore , A > B, answer to the qn is NO =====) SUFFICIENT

2. b <=1
two cases , a > 1 and a<1
case i: a>1 , say 2 , b = 1 (say) , as weknow the case of b=1
from the statement 1,
therefore , A > B, answer to the qn is NO

case ii: a <1 , but a > b , because in A , the denominator cannot be negative or zero
say a = 0.8 and b=0.5
A ==> 2 x 0.8 / (0.8^2 - 0.5 ^2) = 1.6 / (0.64 - 0.25) = 1.6 / (0.39) = ~ 4
B ==> (0.8 x 0.5) + 1 / ( 0.8 x0.5) ^2
1.4 / (0.16) = ~ >8
==> A < B answer to the qn is YES

therefore, INSUFFICIENT
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Kunal takes ‘a’ days to complete a work while Sandeep takes ‘b’ less d 01 Jul 2025, 13:09
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