A cistern is normally filled in 4 hours but takes two hours longer to fill because of a leak in its bottom. If the cistern is full, the leak will empty it in? Choose the most appropriate option.
A) 33 B) 88 C) 40 D) 99 E) 12
1/4 - 1/x = 1/6   x = 12   Answer: 12
<result>E</result>
A cistern is normally filled in 4 hours but takes two hours longer to fill because of a leak in its bottom. If the cistern is full, the leak will empty it in?