# Water fills the tub in 12mins, and empties the tub in 20min when the lid is open. How long will it take to fill an empty tub if the lid is open? Answer: 30min. How do I solve it?

##### 1 Answer

Mar 11, 2018

Suppose,the whole volume of the tub is

so,during filling of the tub,

in

so, in

For emptying,

in

in

Now,if we consider that in

so,

or,

so,

so,