Question

It takes 7 minutes to fill a bathtub using coldwater faucet alone. It takes 12 minutes using the hot water faucet alone. How long will it take to fill the tub using both?

Answer 1

By using both the faucets bathtub gets filled in `4.42` minutes

Explanation:

By cold water faucet `7` minutes to fill `1` bathtub

or

`1` minute to fill `1/7` bathtub
Similarly;
By hot water faucet `12` minutes to fill `1` bathtub

or

`1` minute to fill `1/12` bathtub

By using both we can write
`1` minute to fill `(1/7+1/12)` bathtub

or

`1`minute to fill `(1/7+1/12)` bathtub

or

`1` minute to fill `((12+7)/84)` bathtub

or

`1` minute to fill `((19)/84)` bathtub

or

`((19)/84)` bathtub gets filled in `1` minute

or

`1` bathtub gets filled in `84/19` minutes

or

`1` bathtub gets filled in `4.42` minutes

Therefore by using both the faucets bathtub gets filled in `4.42` minutes