A cistern can be filled in 10 hours but due to a leak, it takes two more hours for the cistern to get filled. What is the time taken by the leak to empty a full cistern?

Explanation

The given details are,
When there is no leakage A pipe can fill the cistern in = `10` hours.
In `1` hour without leakage A pipe can fill the cistern in =` 1/10` parts.
When there is leakage cistern gets filled in = `12` hours
In 1 hour, when there is leakage cistern gets filled in = `1/12` parts.
In 1 hour, due to leakage cistern gets filled to = `1/10 – 1/12`
= `(12-10)/120`
`= 2/120`
= `1/60` part.
Now total time taken to emptied by the leak is `1/(1/60)=60` hours.