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# (Fraction)Over the course of a year...

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Intern
Joined: 07 Feb 2018
Posts: 1
(Fraction)Over the course of a year...  [#permalink]

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10 Jan 2019, 20:58
Don’t know how to make a equation. It will be really grateful if you guys teach me.

Q. Over the course of a year a certain factory increased its output by 90 percent. At the same time it decreased its total working hours by 20 percent. By what percent did this factory increase its output per hour?

A. 70%
B. 110%
C. 112.5%
D. 137.5%
E. 237.5%

Sent from my iPhone using GMAT Club Forum mobile app
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 9705
Location: Pune, India
Re: (Fraction)Over the course of a year...  [#permalink]

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10 Jan 2019, 21:25
JUNGWOOLEE wrote:
Don’t know how to make a equation. It will be really grateful if you guys teach me.

Q. Over the course of a year a certain factory increased its output by 90 percent. At the same time it decreased its total working hours by 20 percent. By what percent did this factory increase its output per hour?

A. 70%
B. 110%
C. 112.5%
D. 137.5%
E. 237.5%

Sent from my iPhone using GMAT Club Forum mobile app

Output/Hour = Total Output / Total time in hrs

New Output/Hour = Total Output*(190/100) / Total time in hrs (80/100) = (Output/Hour) *(19/8)

(New Output/Hour) / (Output/hour) = 19/8

This is an increase of 11/8 i.e. (11/8)*100 = 137.5%
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Karishma
Veritas Prep GMAT Instructor

Math Expert
Joined: 02 Sep 2009
Posts: 58402
Re: (Fraction)Over the course of a year...  [#permalink]

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10 Jan 2019, 22:16
JUNGWOOLEE wrote:
Don’t know how to make a equation. It will be really grateful if you guys teach me.

Q. Over the course of a year a certain factory increased its output by 90 percent. At the same time it decreased its total working hours by 20 percent. By what percent did this factory increase its output per hour?

A. 70%
B. 110%
C. 112.5%
D. 137.5%
E. 237.5%

Sent from my iPhone using GMAT Club Forum mobile app

Proper version of this question is here: https://gmatclub.com/forum/over-the-cou ... 89373.html

Rules of posting on the forum: https://gmatclub.com/forum/rules-for-po ... 33935.html
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Re: (Fraction)Over the course of a year...   [#permalink] 10 Jan 2019, 22:16
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