<p>A friend of mine just sent me this riddle. I think I am close to the answer…haha…but think I might be missing something.
Anyone game to see what they get? </p>
<p>It takes one day to fill the vat with this large pipe, two days with that; the third pipe needs but one day more; the fourth pipe fills the vat in four. If all four pipes run together, how long before the task is done?</p>
<p>I get 12/25ths of a day, but maybe there’s some trick I’m missing.</p>
<p>Is this a riddle or just an algebra problem? If it’s just algebra with no tricks, then it’s 0.48 days, or, as Cardinal Fang said, 12/25ths of a day.</p>
<p>That’s what I get, too…but thinking it is way too easy! I keep wondering about the wording for the second pipe. What do you think…just easy or hidden meaning???</p>
<p>I think the wording is just to make it rhyme.</p>
<p>I get 11.52 hours (or 11 hours 31 minutes or .48 days).</p>
<p>Pipe 1 takes 24 hours to fill the vat. In one hour, 1/24 of the vat is filled.
Pipe 2 fills 1/48 of the vat in 1 hour. Pipe 3 fills 1/72 in one hour. Pipe 4 fills 1/96 in one hour.</p>
<p>So let’s let X be the numbers of hours it will take to fill the whole vat.</p>
<p>x/24 + x/48 + x/72 + x/96 = 1 (or the whole vat is filled)</p>
<p>25x/288 = 1</p>
<p>X=11.52 hours</p>
<p>I think ellen has it right on the math, but I’ve been looking for a trick too. Like- the old joke what’s a henway?</p>
<p>Could it possibly be “run together”? In the sense that if all 4 pipes were put together, connected into one long pipe, then the vat could fill only as fast as the smallest pipes’ capacity which is a 4 day fill. I am just guessing here, but the pipes “together” may not mean all pipes running concurrently and separately. Or, I may be all wrong!</p>
<p>Great puzzle; waiting to hear the answer.</p>
<p>Meh…presented as a riddle but in reality it turned out to be just a regular math problem. 
I love riddles but tend to overanalyze them. She said she is getting me warmed up for some real brain teasers. Will see what she sends next. ;)</p>