SOLUTION: Three boys can build a fence in 6 hours, 7 hours, and 8 hours working individually. How long will it take to build the fence if the boys work together?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Three boys can build a fence in 6 hours, 7 hours, and 8 hours working individually. How long will it take to build the fence if the boys work together?      Log On


   

Question 633851: Three boys can build a fence in 6 hours, 7 hours, and 8 hours working individually. How long will it take to build the fence if the boys work together?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Three boys can build a fence in 6 hours, 7 hours, and 8 hours working individually.
How long will it take to build the fence if the boys work together?
:
Let t = the time required when the three work together
Let the completed job = 1
:
Each will do a fraction of fence, the three fractions add up to 1
:
t%2F6 + t%2F7 + t%2F8 = 1
Least Common Multiple would be 168, multiply eq by 168, results
28t + 24t + 21t = 168
73t = 168
t = 168/73
t ~ 2.3 hrs
:
:
You can confirm this, calculate
2.3/6 + 2.3/7 + 2.3/8