(This is an old chestnut of a puzzle, but with a slight twist)

It takes six minutes for just the cold tap to fill my bath with water.

The hot tap fills the bath at the same rate, but unfortunately (due to some strange plumbing) after the hot tap has been running for three minutes its supply of water shuts off for a full two and a half while the hot water tank refills and reheats - after the two and a half minutes, the hot tap commences dispensing water once again.

With the plug pulled out, a full bath empties (at a uniform rate) in only four minutes.

With the hot water tank full and the plug pulled out, how long will it take my bath to fill if I turn both taps on?

right ill try the forward method this time..

every 11/2 minutes the tub fills 1/24
after after 11/2 * 18 = 99 minutes the tub
is 18/24 full at the end of a cycle.

during the cold+hot the tub fills at
2/6 - 1/4 = 2/24 rate. during this time
the fill is 2/24 * 3 = 6 / 24.

18/24 + 6/24 = 24/24
99 + 3 = 102

102 minutes?

Posted by Cheradenine on 2002-07-03 05:54:02