|
Question 989011: Robert can paint a room in 12 hours. Dennis and Vince can paint the room in 10 hours and 9 hours, respectively. If Dennis and Vince work together for 2 hours, how long will it take Robert to finish the job?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Robert can paint a room in 12 hours. Dennis and Vince can paint the room in 10 hours and 9 hours, respectively. If Dennis and Vince work together for 2 hours, how long will it take Robert to finish the job?
---
Robert rate:: 1/12 job/hr
Dennis rate:: 1/10 job/hr
Vince rate:: 1/9 job/hr
---------
time*rate = work done
-------------
2(1/10 + 1/9) = 2(19/90) = 19/45 job done by D and V together
----
(1/12)x = 1 - (19/45)
-----
(1/12)x = 26/45
x = 12*26/45
x = 6.93 hours (time for Robert to finish the job)
----------
Cheers,
Stan H.
|
|
|
| |
