SOLUTION: Working for 8 hrs daily, 40 men can complete in 21 days. Working for 10 hrs daily, If the work has to be finished in 14 days, how many men are needed to do the same work?

Question 949656: Working for 8 hrs daily, 40 men can complete in 21 days. Working for 10 hrs daily, If the work has to be finished in 14 days, how many men are needed to do the same work?
Answer by ptaylor(2198) (Show Source): You can put this solution on YOUR website!
Working for 8 hrs daily, 40 men can complete in 21 days. Working for 10 hrs daily, If the work has to be finished in 14 days, how many men are needed to do the same work?
Let x=amount of men needed to do the same work
At 8 hr/da, 40 men can complete the job in 8*21=168 hrs
So 40 men work at the rate of 1/168 of the job/hr
1 man works at the rate of 1/(40*168)=1/6720 of the job per hour
At 10 hr/da, work must be finished in 14*10= 140 hr
x men works at the rate of 1/140 job/hr
So our equation to solve is:
x/6720=1/140
6720=140x
x=48 men---needed to do the same work working at 10 hr/da for 14 days.
CK
48/6720 = 1/140
1/140=1/140
Another way
It takes 40*168=6720 man-hours to complete the work
Working 14 days at 10 hrs/da, x men takes 140 hrs to complete the work
140x=6720
x=48
Hope this helps---ptaylor

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