I know this question's answer, but i want to know solution. ! will you help me ?!!
problem/
Jim can fill a pool carrying bucks of water in 30 minutes. Sue can do the same job in 45 minutes. Tony can do the same job in 1 ½ hours. How quickly can all three fill the pool together?
answer' 15 min
2007-01-01 17:19:12 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Jim's rate is 1/30 pools/min
Sue's is 1/45
Tony's is 1/90
their combined rate is
1/30+1/45+1/90=(3+2+1)/90=6/90=1/15 pools per minute
therefore 1 pool/(1pool/15min)=15 min.
2007-01-01 17:28:49 · answer #1 · answered by yupchagee 7 · 15⤊ 0⤋
Jim does 1/30 of the job each minute, Sue 1/45, Tony 1/90. If t is the time to do the whole job, t/30 + t/45 + t/90 = 1
3t + 2t + t = 90
6t = 90
t = 15 minutes.
2007-01-02 01:50:11 · answer #2 · answered by Philo 7 · 0⤊ 0⤋
Technically, there is no determinable answer.
Afterall, who is to say that when they are trying to fill the pool again together, that they will all work as hard as before? Tony, the slowest of the three, may think that his efforts are useless and will rely on Jim, the fastest, (and maybe even Sue also) to fill the pool by themselves. And even then, they might not be working at the same rate.
/endramble
However, if you'd like to solve it the way the problem would like you to, do this:
Take all of these rates into fraction form (x=pools filled in the denominator's length of time):
x/30 , x/45 x/90 (90minutes in 1.5hrs)
And add these rates together:
(3x/90) + (2x/90) + (x/90)
= 6x/90
Simplify:
x/15 <-- this is a RATE not a divison problem (like 50mi/1hr)
So, collectively, they can fill one pool (1x) in 15minutes).
Now you know the TRUE answer and what the alleged one is.
2007-01-02 01:43:42 · answer #3 · answered by Novy 5 · 0⤊ 0⤋
Work done by Jim in 1 minute=1/30 work
Work done by Sue in 1 minute=1/45 work
Work done by Tony in 1 minute=1/90 work
If they were doing it together=1/30+1/45+1/90
6/90work in 1 minute
90/6=15 minutes if they were working together.
Answer=15 minutes.
2007-01-02 01:26:09 · answer #4 · answered by Nitin T F1 fan 5 · 0⤊ 0⤋
1/30 + 1/45 + 1/90 = 1/t or
t = 1/(1/30 + 1/45 + 1/90)
On your calculator, punch 30[1/x] + 45[1/x] + 90[1/x] [=] [1/x]
and you have the answer.
2007-01-02 02:08:21 · answer #5 · answered by Anonymous · 0⤊ 0⤋
I like to explain these like so: the formula is "rate x time = 1 job". So to get the rate at which a person works, take the reciprocal of the time the person takes to do the job. Then to get the rate at which people work together, you just add the rates at which each one works. To find the time needed working together, take the reciprocal of that sum.
2007-01-02 01:25:38 · answer #6 · answered by John D 3 · 0⤊ 0⤋
i think the answer is 45 mins
2007-01-02 01:27:32 · answer #7 · answered by i,m here if you need to talk. 6 · 0⤊ 1⤋
im sorry but i have no clue...im horrible at math
2007-01-02 01:22:07 · answer #8 · answered by Sarah M 2 · 0⤊ 1⤋