Jim can fill a pool carrying buckets of water in 30 min. Sue can do the same job in 45 mins. Tony can do the same job in 90 mins. How long will it take all three to fill the pool together?
2007-03-23 05:27:49 · 2 answers · asked by Kyle K 1 in Education & Reference ➔ Homework Help
Start my changing from time to rate.
Jim fills the pool at a rate of 2 pools/hour.
Sue does it as 4 pools / 3 hours.
Tony does it at 2 pools / 3 hours.
Change 2/1 to 6/3 and we have three fractions we can add up:
6/3 + 4/3 + 2/3 = 12/3 = 4/1; together they can fill 4 pools in an hour. Thus, filling one pool will take 15 minutes.
Does that answer make sense? Well, Jim can fill half the pool in 15 minutes. Sue can fill 1/3 of the pool in 15 minutes. Tony can fill 15/90=1/6 of the pool in 15 minutes. And 1/2 + 1/3 + 1/6 = 3/6 + 2/6 + 1/6 = 1 whole, which shows our answer is correct.
2007-03-23 05:36:13 · answer #1 · answered by William S 3 · 1⤊ 0⤋
90 + 30 +45 = ....
2007-03-23 13:01:59 · answer #2 · answered by Ghost 2 · 0⤊ 0⤋