Expert: Abe Mantell - 1/6/2009

Question
I have one bucket and 2 faucets.  One faucet can fill the bucket alone in 6 minutes.  The other faucet can fill the bucket alone in 4 minutes.  How many seconds will it take to fill the bucket with both faucets on?

Answer
Hello Stacey,

Since work = (rate of work)x (time), we get:
The rate of work for the first faucet is 1 bucket in 6 minutes, or
1/6 of a bucket/minute.
For the second faucet, it is 1/4 of a bucket/minute.

Together, the rate is 1/6 + 1/4 bucket/minute = 10/24 = 5/12 bucket/min.

Now let t=the time to fill the bucket with both faucets on.  Thus,
(5/12)t=1 (i.e. 1 bucket)...solving for t gives t=12/5 minutes
or 2.4 minutes = 2 minutes 24 seconds = 144 seconds.

OK?  I hope this helps!

TTYL, Abe