Question

Working together takes two different size hose 30 minutes to fill a small swimming pool if it takes 40 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

So when the pool is filled by the two hoses together in 30 minutes, the larger hose itself fills 30/40 = 3/4 of the pool. That means in those 30 minutes the smaller hose fills 1/4 of the pool; and that means it would take the smaller hose 30*4 = 120 minutes to fill the pool alone.