## CS Folks Forgetting Basic Algebra

Its been 10 years since I graduated high school so when this Math problem came up I had to look twice. My bro was given a little algebra puzzle which I helped him with. After finishing it up I decided to write it all up and ask fellow co-workers (without giving them answers of course) this same problem.

Whether they could do it or not I didn't really care..I just wanted an answer...any answer. It is amazing from our IT staff that rarely anyone got it right. How did folks who got MBAs in MI and BS degrees in various other colleges get stumped by a simple algebra problem.

I decided to post it here to see what others across the world can come up with. Its pretty straightforward and a lot of people do have an idea of how to solve it but they always end up saying well there is one piece of missing information..which is true however even with that missing piece you can solve it.

Ok so the problem:

You have a bath tub in which has 4 faucets (I know pretty odd). One faucet can fill the entire tub in 1 hour. The second faucet can fill the tub in 45 minutes. The third faucet can fill it up in 30 minutes. And finally the last one can fill the entire bath tub in only 15 minutes (note the number of minutes for each faucet is based on the faucet turned on by itself).

Now that you have this info the problem is how long would it take to fill the tub if all faucets are turned on at the same time?

Here is a photo to help :):

Bathtub (4 faucets)

Please no put downs on wrong answers, this is just for us folks who haven't done some algebra in a real long time!!! Tell us your answer, draw it if you have to, just give an answer **even if you don't know it, post it!**

**PS: Mladen you are not allowed to play since you already tried. =)**

# Legacy Comments

CalmYourself
2007-08-20 |
re: CS Folks Forgetting Basic Algebra 7 Minutes, 12 seconds. |

WILDGUESS
2007-08-20 |
re: CS Folks Forgetting Basic Algebra 28.8 minutes |

WILDGUESS
2007-08-20 |
re: CS Folks Forgetting Basic Algebra 28.8 minutes |

Rob
2007-08-20 |
re: CS Folks Forgetting Basic Algebra The taps put in 1, 4/3, 2, 4 tanks per hour respectively. So if they're all on, that should make 8.33 tanks per hour, which means 0.12 hours per tank. 0.12 hours is 7.2 mins, or 7:12 |

Mladen
2007-08-20 |
re: CS Folks Forgetting Basic Algebra ha ha... :) |

Siva G
2007-08-20 |
re: CS Folks Forgetting Basic Algebra 7.2 minutes. |

Suresh
2007-08-20 |
re: CS Folks Forgetting Basic Algebra 1/60+1/45+1/30+1/15 = 25/180 = 5/36. 36/5 minutes. |

Jon
2007-08-20 |
re: CS Folks Forgetting Basic Algebra Suresh, We think alike! Rob, Didn't think about it in terms of hours, nice job. |

Matthew
2007-08-20 |
re: CS Folks Forgetting Basic Algebra 7.2 minutes |

sirrocco
2007-08-21 |
re: CS Folks Forgetting Basic Algebra 7.2 minutes. Suresh's formula is the way to go :) |

David Gugick
2007-08-21 |
re: CS Folks Forgetting Basic Algebra Common Demoninator is 3 hours, so 3x + 4x + 6x + 12x = 3 hours 25x = 3 x = .12 hours 60 * .04 = 7.2 min = 7min 12 sec or the verbose method 3 hours = 180 min 60 minute faucet fills 3 tubs in 3 hours 45 minute faucet fills 4 tubs in 3 hours 30 minute faucet fills 6 tubs in 3 hours 15 minute faucet fille 12 tubs in 3 hours Therefore, in 180 minutes we have filled 25 tubs 25 tubs/180 minutes = 1 tub / x minutes 25x = 180 x = 7.2 minutes |

Rob
2007-08-22 |
re: CS Folks Forgetting Basic Algebra Jon, My method just seemed to be the most practical, which is generally the easiest way to solve things. Like the question about "if it takes someone 12 minutes to saw a piece of wood into 3 pieces, how long to cut it into four?", thinking practically is best. Rob |

Scott
2007-08-22 |
re: CS Folks Forgetting Basic Algebra To see a concrete example, say the tub is 60 gallons. Then: Faucet 1 fills 1 gal / minute Faucet 2 fills 1 1/3 gal / minute Faucet 3 fills 2 gal / minute Faucet 4 fills 4 gal / minute All together, they pour 8 1/3 gal / minute into the tub. So 60 gallons takes 60 gal / (8 1/3 gal / min) = 7.2 minutes (7 min 12 sec), just as the formulas indicate. I prefer formulaic solutions, but sometimes a concrete case makes it simple. Scott |

Peter Larsson
2007-08-24 |
re: CS Folks Forgetting Basic Algebra The problem statement would have been more fun if there also was a drain! For example, opening the drain empties the bathtub in 4 minutes. When having an completely open drain, is it still possible to fill the tub with the four faucets? |

Peter Larsson
2007-08-24 |
re: CS Folks Forgetting Basic Algebra The problem statement would have been more fun if there also was a drain! For example, opening the drain empties the bathtub in 4 minutes. When having an completely open drain, is it still possible to fill the tub with the four faucets? And it it is possible, how long time will it take to fill the tub when drain is open? |

Maitus
2008-08-14 |
re: CS Folks Forgetting Basic Algebra I got it! Thank goodness you did not ask me to remember calculus... |