Question

One hose can fill a goldfish pond in 36 ​minutes, and two hoses can fill the same pond in 20 minutes. Find how long it takes the second hose alone to fill the pond.

Answer 1

Answer:

45 minutes

Step-by-step explanation:

It is given that one hose can fill a goldfish pond in 36 minute

So the the first hose can fill goldfish pond $\frac{1}{36}$ per minute

When both fill together then they fill in 20 minutes

So the the both  hose can fill goldfish pond $\frac{1}{20}$ per minute

Let Goldfish pond filled by second hose  $\frac{1}{x}$ per minute

so $\frac{1}{36}+\frac{1}{x}=\frac{1}{20}$

$\frac{1}{x}=\frac{1}{20}-\frac{1}{36}$

x=45 minutes

Answer 2

Answer:

The time taken by the second hose alone to fill the pond is 45 minutes.

Step-by-step explanation:

One hose can fill a goldfish pond in 36 ​minutes.

Let second hose can fill the pond alone in x minutes.

The part of goldfish pond filled by one hose in 1 minute is $\frac{1}{36}$.

The part of goldfish pond filled by second hose in 1 minute is $\frac{1}{x}$.

Two hoses can fill the same pond in 20 minutes.

The part of goldfish pond filled by both hose in 1 minute is $\frac{1}{20}$.

$\frac{1}{36}+\frac{1}{x}=\frac{1}{20}$

$\frac{x+36}{36x}=\frac{1}{20}$

$20(x+36)=36x$

$20x+720=36x$

$720=36x-20x$

$720=16x$

$\frac{720}{16}=x$

$45=x$

Therefore, the time taken by the second hose alone to fill the pond is 45 minutes.