Question

Working together, it takes two different sized hoses

20
minutes to fill a small swimming pool. If it takes
25
minutes for the larger hose to fill the swimming pool by itself, how long will it take the smaller hose to fill the pool on its own?

Answer 1

Using one small hose speed ups filling the pool by 5 minutes. Therefore, five small hoses can fill the pool without the need of large hose in 25 minutes.
One small hose needs: 25 × 5 = 125 minutes to fill the pool.