24 men working at 8 hours per day can do a piece of work in 15 days. In how many days can 20 men working at 9 hours per day do the same work?
Given: Number of men working 8 hours a day for 15 days = 24
To find: Number of days required for 20 men working 9 hours a day to do the same work.
Number of days required for 1 man working 8 hours to complete the work = 
= 0.625
Number of days required for 1 man working 1 hour to complete the work = 
= 0.078125
Number of days required for 20 men working 1 hour to complete the work = 0.078125x20 = 1.5625
Number of days required for 20 men working 9 hours per day to complete the work = 1.5625x9 = 14.06 days
∴ Number of days required for 20 men working 9 hours a day to complete the work is 14.06 days.
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