Question

20 men complete one-third of a work in 20 days. How many more men should be engaged to finish the rest of the work in 25 more days?

Answer 1

let x more men required to complete the work

20 men -------- 20 days --------- 1/3 of work

20 men -------- 60 days --------- full of work

1 man -------- 1200 days --------- full of work

so

x men -------- 1200/x days --------- full of work

also

20 men -------- 5 days --------- 1 / 12 of work

20 men completes 1/3 of work initially

20 men completes 1/3 of work for next 20 days

and same 20 men completes the 1/12 of the work in 5 days

so completed work is

1/3+1/3+1/12 = 9/12 = 3/4

remained 1/4 work can complete in 25 days by x men

x men -------- 1200/x days --------- full of work

x men -------- 300/x days --------- 1/4 of work

but 300/x =25 days

so x = 300/25

x = 12 men more required