40 men take 60 hours to refine 200 units of stone. How long will it

Question

40 men take 60 hours to refine 200 units of stone. How long will it take 60 men to refine 800 units of stone if the new team is 20% less efficient?

A. 20 hours
B. 25 hours
C. 200 hours
D. 240 hours
E. 250 hours

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BongBideshini · Answer

Men 
 Efficiency (units/hr) 
 time 
 total work 
 
  40 M 
 =200/60 
 60 
 200 
 
  1 M 
 =200/(60*40)
=1/12

1 M
 
 new efficiency
=0.8/12
=1/15

60 M 
 =60/15
=4

60 M 
 4 
 =800/4
=200 
 800 
 
  Ans 
  
  200

Ans C

amansoni5 · Answer

Base rate: 40×60=2400 man-hours produce 200 units ⇒ 1 man-hour = 1/12 unit.

New efficiency is 20% lower ⇒ rate becomes 1/12×0.8=1/15 per man-hour.

With 60 men: total rate = 60×1/15=4 units/hour.

Time for 800 units = 800/4=200 hours.

Answer: C (200 hours)

Adit_ · Answer

40*60*Rate = 200.
Rate = 1/12

New team = 0.8*Rate = 4/60.

x*60*4/60 = 800.
4x = 800.
x = 200.

Answer:  Option C

vasu1104 · Answer

rate = work / time
rate = 200 / 60 = 10/3
this is for 40 men rate. so 1 man rate is 10 / (3*40) = 1/12

now new team is 20% less efficient means only 80% of old rate. so that is (4/5) * (1/12) = 1/15
now this rate is for 1 man so rate for 60 men = 4.
now time = 800 / 4 = 200
option C

thisisakr · Answer

Work rate = 200/(40×60) = 1/12 units/man-hour 
 At 80% efficiency: 1/12*0.8 = 1/15 units/man-hour

Time = 800 unit / (60 men × 1/15 unit/man-hour ) = 800 ÷ 4 =    200 hours   .

Answer  C

ExpertsGlobal5 · Answer

C is the correct answer choice.

Video explanation:

https://www.youtube.com/watch?v=OkK0RE4DHvw

40 men take 60 hours to refine 200 units of stone. How long will it

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Men	Efficiency (units/hr)	time	total work
40 M	=200/60	60	200
1 M	=200/(60*40) =1/12
1 M	new efficiency =0.8/12 =1/15
60 M	=60/15 =4
60 M	4	=800/4 =200	800
Ans		200

GMAT Problem Solving (PS) Questions

40 men take 60 hours to refine 200 units of stone. How long will it

Prep Toolkit

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