John does a work in 6 hours. Silvester does the same work in 4 hours. If they both work together?
In how many hours will they complete the work...........plzzzz show working.........thank u very much
- JohnLv 71 decade agoFavorite Answer
If John does it in 6 hours, he can complete 1/6 of the job in one hour. Silvester can do 1/4 of the job in an hour.
How long it will take them is their combined work effort = 1/6 + 1/4 = times the time it takes them. And they'll complete ONE whole job.
t*(1/4 + 1/6) = 1. 1/4 + 1/6 = 5/12.
t(5/12) = 1.
t = 12/5 = 2.4 hours or 148 minutes.
- 1 decade ago
John = 1/6 jobs/hr
Silvester = 1/4 jobs/hr
John and Silvester = 1/6 + 1/4 = 5/12 jobs/hr
Time = 12/5 or 2.4 hrs/job
- JGLv 51 decade ago
John's rate is 1/6 of the task per hour
Silvester's is 1/4 of the task per hour
Together they do 1/4 + 1/6 = 3/12 + 2/12 = 5/12 of the task per hour.
So it will take 12/5 hours which is 2.4 hours or 2 hours, 24 minutes.
- Andrew KLv 61 decade ago
First quantify the word problem.
Rate of work x time = work
Find the rate of work for John:
R* 6 hr = 1
R = 1/6
Rate of work for SIlvester.
R*4hr = 1
Now with both their rates of work, which will remain the same, and the amount of work, which will remain the same, solve for time.
12/5 hr = T
2 2/5 hr = 2 hours 24 minutes
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- ComoLv 71 decade ago
Let work to be done = X units
rate of work (units/h)___X/6________X/4
Working together , the work done per hour is:-
X/6 + X/4 = 2X/12 + 3X/12 = 5X/12
Time = Work done / rate of work
Time = X / 5X/12 h
Time = 12/5 h = 2 2/5 h = 2h 24 min