Question

19 men working 7.5
hours a day can finish a job in 21 days. How many hours a day must
45 men work to complete it in 7 days?
​

Answer 1

Step-by-step explanation:

19 men take 21 days working 15/2 hours per day.

Hours per day 45 men will take to complete in 7 days will be:

if 19 men = 15/2 hours

then 45 men = 19/45 hours ( this because the 45 men will take less hours per day, hence you use the lesser fraction of the two values)

if 21 days = 15/2 hours per day

then 7 days= 21/7 (this because the hours required will be more, hence you use the larger fraction of the two values)

therefore the calculation is = 15/2 x 19/45 x 21/7

= (15x19x21)/(2x45x7)

= 19/2

= 9.5 hours per day