Question

A cistern is normally filled in 8 hrs, but it takes 2 hours longer to fill because of a leak in its bottom. If the cistern is full, the leak will empty it in.

• A. 35 hours
• B. 45 hours
• C. 40 hours
• D. None of these

Answer 1

The correct option is C 40 hours

Here, x = 8 and y = 8 + 2 = 10.
$\therefore$ The leak will empty the cistern in

$=\left(\frac{xy}{y-x}\right)hours$

$=\left(\frac{8\times 10}{10-8}\right)hoursor,40hours$