Bob can do a job in 5 hours while Bill can do the same job in 8. How many hours would it take them, working together, to do this job? Thanks!!!
Mathematics · Middle School · Thu Feb 04 2021
Answered on
Given :
Bob can do a job in 5 hours, so Bob's rate = 1/5 job per hour
Bill can do a job in 8 hours, so Bill's rate = 1/8 job per hour.
Let x be the total work.
So, according to question equation will be
1/5 + 1/8 = 1/x
Taking L.C.M.
(8 + 5)/40 = 1/x
13/40 =1/x
Cross - Multiplying, we get
13x = 40
Dividing both sides by 13, we get
13x/13 = 40/13
x = 3 1/13 hours or 3 hours 5 mins ( approx.)