the work takes 120 man-days
10 men and 5 boys is like 12.5 men
120 / 12.5 = ?
If 6men can do a piece of work in 20 days and one man can do a work of 2 boys.Find how many days can 10 men and 5 boys do the same work ?
2 answers
man-days = 6(20) = 120
rate of man = 1/120 , where 1 represents the work done
rate of boy = 1/240
x(10)(1/120) + x(5)(1/240) = 1 , where 1 represents the work
x/12 + x/48 = 1
x(1/12 + 1/48) = 1
(5/48)x = 1
x = 48/5 = 9.6 days
or
since 1 boy does the job of 1/2 man, 5 boys ---> 2.5 men
so we have 10 men + 5 boys = 12.5 men
if 6 men can do the job in 20 days ---> 120 man-days
12.5 men can do it in 120/12.5 or 9.6 days
rate of man = 1/120 , where 1 represents the work done
rate of boy = 1/240
x(10)(1/120) + x(5)(1/240) = 1 , where 1 represents the work
x/12 + x/48 = 1
x(1/12 + 1/48) = 1
(5/48)x = 1
x = 48/5 = 9.6 days
or
since 1 boy does the job of 1/2 man, 5 boys ---> 2.5 men
so we have 10 men + 5 boys = 12.5 men
if 6 men can do the job in 20 days ---> 120 man-days
12.5 men can do it in 120/12.5 or 9.6 days
1 answer