Posted by **Celina** on Monday, May 28, 2012 at 11:11am.

Twelve man take 6 hours to finish a piece of work. After the 12 men have worked for 1 hour, the contractor decides to call in 8 men so that the work can be completed earlier. How many more hours would 20 men take to complete the remaining work?

- Mathematics -
**Reiny**, Monday, May 28, 2012 at 11:20am
job requires 12(6) = 72 man-hours

They work for 1 hour, so 12 man-hours are used up, leaving 60 man-hours for the job to be done

Second shift has 20 men,

so time needed to complete the job

= 60 man-hours/20 men

= 3 hours

(the above applies only in theory, it does not apply to city workers or the like. Doubling the number of men on a job in practise does not cut the required time in half. , (this is supposed to be a joke) )

- Mathematics -
**Celina**, Monday, May 28, 2012 at 11:31am
Thanks!

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