Working 10 hours a day, Polas can Complete a work in 4 days. Working 3 hours a day, Mahin can complete the same work in 20 days. Working 4 hours a day, they can jointly complete the work in

Questin: Working 10 hours a day, Polas can Complete a work in 4 days. Working 3 hours a day, Mahin can complete the same work in 20 days. Working 8 hours a day, they can jointly complete the work in

Solution:
Given,
Working 10 hours a day, Polash can complete the work in 4 days
Polash's total working hour = (10 × 4) hours
= 40 hours

∴ Polas's 1 hour's work = 1/40 part

Working 3 hours a day, Mahin can complete the work in 20 days
Mahin's total working hour = (3 × 20) hours
= 60 hours

∴ Mahin's 1 hour's work = 1/60 part

( Polas + Mahin )'s 1 hour's work = (1/40 + 1/60) part
= ( 3 + 2)/120 part
= 5/120
= 1/24 part

So (Polas + Mahin) complete whole part = 24 hours

Hence, they work 8 hours a day
i.e. they require 3 days to complete the work.