THE QUESTION:
Rhonda and Sandra are stuffing envelopes to raise funds for a school trip. if rhonda did the whole job herself, it would take her 5hours. If sandra worked on her own it would take her 4 hours. How long does it take both of them working together and starting at the same time, to do the job?
Please state your working and explanations :D THANKS
THE ANSWER:::::::::::::::::::::::::::::::::::::::::
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2hours 13mins
2007-01-24 21:08:26 · 7 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
x/5 + x/4 = 1
x is the amount of time it took both of them. The x/5 is the amount of time it took Rhonda to do her part of the job, x/4 is the amount of time it took Sandra to do her part. It =1 because there is only 1 job to do.
Solve for x:
x/5 + x/4 = 1
4x/20 + 5x/20 = 1
9x/20 = 1
9x = 20
x = 2 2/9 = 2 hours and 13 minutes.
(2/9 * 60 = 13.33333 - round to 13)
2007-01-24 21:14:56 · answer #1 · answered by Mathematica 7 · 1⤊ 0⤋
Rhonda in one hour does 1/5 of the work
Sandra in one hour does 1/4 of the work
Whe working together they do in 1 hour 1/4+1/5 of the work
1/4+1/5 = 5/20 + 4/20 = 9/20 of work in1 hour
so for all the work time 1/(9/20) = 20/9 hours = 2hours+120/9 minutes = 2hours 13 minutes
2007-01-24 21:17:01 · answer #2 · answered by maussy 7 · 0⤊ 1⤋
in 1hour:
Rhonda did 1/5 of her work
Sandra did 1/4 of her work
Both did 1/4 +1/5 = 9/20 of their work
they finish working in 1/(9/20) = 20/9 hours. That is the correct ans
2007-01-24 21:20:23 · answer #3 · answered by jenkyd 2 · 0⤊ 1⤋
This is a "job" problem. How long does it take to complete one job?
Let
t = time to finish working together
t/5 + t/4 = 1 job
4t + 5t = 20
9t = 20
t = 20/9 hours = 2 hours, 13 minutes, 20 seconds
2007-01-24 23:02:23 · answer #4 · answered by Northstar 7 · 0⤊ 0⤋
x/5 + x/4 = 1
20(x/5)+ 20(x/4) = 20(1)
4x + 5x = 20
9x = 20
9x/9 = 20/9
x = 20/9
x = 2 2/9
2/9(60 = 120/9 = 13.33333333
x = 2 Hours 13 Minutes
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2007-01-24 23:07:11 · answer #5 · answered by SAMUEL D 7 · 0⤊ 0⤋
If there are x envelopes to stuff:
Rhonda's stuffing rate = x/5 envelopes per hour
Sandra's stuffing rate = x/4 envelopes per hour.
So their combined rate = x/5 + x/4 = 9x/20 envelopes per hour
Therefore to stuff x envelopes, they'll together take
x/(9x/20) = 20/9 = 2 2/9 hours
2007-01-24 21:20:42 · answer #6 · answered by statistician 1 · 0⤊ 1⤋
Did the teacher or book give you any examples as guides for solving them? That is a good way to develop a feel for working them. Maybe give some specific ones which are causing you trouble?
2016-03-29 01:38:30 · answer #7 · answered by Anonymous · 0⤊ 0⤋