SOLUTION: Together Bill and Fred working at the same rate rake a yard in an hour and a half. If three of their friends had joined them at the start and also worked at the rate, it would have

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Together Bill and Fred working at the same rate rake a yard in an hour and a half. If three of their friends had joined them at the start and also worked at the rate, it would have      Log On


   

Question 653004: Together Bill and Fred working at the same rate rake a yard in an hour and a half. If three of their friends had joined them at the start and also worked at the rate, it would have taken them ___ minutes for the five of them to rake the yard.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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Together Bill and Fred working at the same rate rake a yard in an hour and a half.
If three of their friends had joined them at the start and also worked at
the rate, it would have taken them ___ minutes for the five of them to
rake the yard.
:
let the completed job = 1
Find the rate (r) using Bill and Fred
:
1.5%2Fr + 1.5%2Fr = 1
Multiply by r
1.5 + 1.5 = r
r = 3 hrs for one man to do the job
:
Let t = time required for 5 to do it
:
t%2F3 + t%2F3 + t%2F3 + t%2F3 + t%2F3 = 1
%285t%29%2F3 = 1
5t = 3
t = 3/5 * 60 min = 36 min when all 5 do the job