Question

It takes Nina 2 hours 30 minutes to fill a swimming pool using 2 hosepipes. How long will it take Nina to fill the pool if she uses 3 hosepipes? [You may assume all the hosepipes supply water at the same rate.] ​

Answer 1

1 hour and 40 minutes

Explanation:

Let's calculate a rate for filling the swimming pool. Lets also convert minutes into hours. Let ZHp stand for 1 hosepipe.

2 hours 30 minutes = 2.5 hours

Assuming the hosepipes deliver water at the same rate, we can say that 1 hosepipe would require 2*(2/5 hr) = 5 hours to fill one swimming pool.

One hose pipe rate = 5.0 (hours/1 pool)

Or we can also say One hosepipe(Hp) = (1 pool)/(5.0 hours)

To fill one pool with 3 Hp:

3 Hp = 3 pools/(5.0 hours)

If we only want 1 pool filled, multiply by (1/3)/(1/3): [Note: (1/3)/(1/3) = 1]

3 pools/(5.0 hours)*(1/3)/(1/3)

(3 pools)*(1/3)/(5.0 hours)*(1/3)

(1 pool )/(5/3) hour

it will take (5/3) hour to fill one pool. That's 1 and 2/3 hour, or 1 hour and 40 minutes.