The hot tap takes 6 minutes to fill the tub alone and

the cold tap takes 4 minutes to fill alone.

So you turn them both on at the same time

but you are unaware that you left the plug out.

The plug empties the tub in 12 minutes.

How long will it take to fill the tub?

#### Click here for Answer

3 minutesSolve this by:

(1/6 + 1/4 - 1/12) ^ (-1)

= (1/3)^(-1) = 3