Question

4 men, each working 6 hours per day can build a wall in 9 days. How long will 6 men, each working 3 hours per day take to finish the same work?

Answer 1

Clearly, ` M propto 1/D and M propto 1/H`
` rArr MDH `= Constant.
` rArr M_(1)D_(1)H_(1)=M_(2)D_(2)H_(2)`
` rArr 4 xx 9 xx 6 = 6 xx D_(2) xx 3`
` rArr d_(2) = 12`.
` :. ` Six men each working 3 hourss per day can finish the job in 12 days.