Question

If 3 men or 6 boys can finish a work in 20 days, how long will 4 men and 12 boys take to finish the same work?

Answer 1

3 men = 6 boys

4 men = `6/3xx4` = 8

Total boys in second case :
= 4 men + 12 boys = 8 + 12 = 20 boys

6 boys can do a piece of work in 20 days

Then let 20 boys will do the same work in x days

∴ 6 : 20 : : 20 : x ........(More boys,less days)

⇒ 6 : 20 : : x : 20 ....(By inverse proportion)

x = `(20xx6)/20` 

= 6 days

∴ They will do the work in 6 days