Barry can do a certain job in 4 hours, whereas it takes Mike 6 hours to do
the same job. How long would it take them to do the job working together?
2007-07-26 02:25:45 · 9 answers · asked by Tazzzy 1 in Science & Mathematics ➔ Mathematics
Let job consist of X units
Barry`s rate of work = (X / 4) units / hour
Mike`s rate of work = (X / 6) units / hour
Working together they complete
X / 4 + X / 6 units in 1 hour
3X / 12 + 2X / 12 units in 1 hour
5X / 12 units in 1 hour
Time for X units = X / [5X / 12 ] hours
Time = 12 / 5 hours
Time = 2 2/5 hours
Time = 2 h 24 min.
2007-07-27 07:14:02 · answer #1 · answered by Como 7 · 0⤊ 0⤋
To do the job together, it would take them 5 hours.
Barry can do 1/4 of the job in an hour, and Mike can do 1/6 of the job in an hour. If you add them together, you get 5/12 of an hour. Then you multiply by 12 to see how much it is totally, which is 5 hours.
2007-07-26 02:31:40 · answer #2 · answered by Anonymous · 0⤊ 1⤋
Barry can do 1/4 of the job in 1 hour (or 3/12)
Mike can do 1/6 of the job in 1 hour (or 2/12)
In one hour they can do 5/12 of the job.
So, it would take them 12/5 hours to complete the job.
2007-07-26 02:30:45 · answer #3 · answered by miggitymaggz 5 · 1⤊ 0⤋
in 1 hour Barry will do 1/4 work and Mike will do 1/6 work
so total work in 1 hour = 1/4+1/6 = 5/12
so it will take 12/5 hours to do whole work i.e. 2 hours 24 minutes
2007-07-26 02:31:09 · answer #4 · answered by Anubarak 3 · 1⤊ 0⤋
(4 x 6) / ( 4 + 6) = 24 / 10 = 12 / 5
It will take 2 hours and 24 minutes.
2007-07-26 02:34:43 · answer #5 · answered by Don E Knows 6 · 1⤊ 0⤋
let the total work done in job be x;
barry work rate is x/4 work per hour.
mike's rate is x/6 work per hour
work done in one hour by both is x/6 + x/4
=10x/24=5x/12;
so time taken = x/(work rate)= 12/5 hours = 2.4 hours= 2 hours 24 mins
2007-07-26 02:31:22 · answer #6 · answered by S R 1 · 1⤊ 0⤋
12 hrs where Barry do 3 jobs while mike 2 jobs..
2007-07-26 02:31:01 · answer #7 · answered by echa r 1 · 0⤊ 1⤋
Rate Barry Works at: j/4hr
Rate Mike Works at: j/6hr
j/4hr + j/6hr = 3j/12hr + 2j/12hr
5j/12hr is their total rate.
Multiply by 12hr/5 to finish job.
12/5 hrs
2007-07-26 02:31:31 · answer #8 · answered by UnknownD 6 · 1⤊ 0⤋
10 days
2007-07-26 03:15:46 · answer #9 · answered by Anonymous · 0⤊ 0⤋