SOLUTION: Worker A finishes the job in 10 hrs; Worker B finishes it in 12 hrs, and worker C finishes it jn 15 hrs. After worker A worked alone for 2 hrs, and then B worked alome for 4 hours,

Question 935751: Worker A finishes the job in 10 hrs; Worker B finishes it in 12 hrs, and worker C finishes it jn 15 hrs. After worker A worked alone for 2 hrs, and then B worked alome for 4 hours, how many hours will it take C alone to finish the remaining work?

Found 2 solutions by ptaylor, josmiceli:
Answer by ptaylor(2198) (Show Source): You can put this solution on YOUR website!
Let x = amount of time it takes worker C alone to finish the job
Worker A works at the rate of 1/10 of the job per hour
Worker B rate is 1/12 of the job per hour
Worker C rate is 1/15 of the job per hour
In 2 hours, worker A finishes (1/10)*2=2/10 = 1/5 of the job
In 4 hours worker B finishes (1/12)*4=1/3 of the job
Together A and B have finished 1/5 + 1/3=3/15+5/15=8/15 of the job leaving 7/15 yet to be finished
So our equation to solve is:
(1/15)*x=7/15
x=7 hours
CK
(1/10)*2+(1/12)*4+(1/15)*7 should equal 1 job
Hope this helps---ptaylor

Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
What fraction of the job did A finish in hrs?
A's rate is: ( 1 job ) / ( 10 hrs )

-----------------------
That means there is of the job left to do
B's rate is ( 1 job ) / ( 12 hrs )
B's fraction of the fraction left to do is:

is the fraction now done
That means there is of the job left to do
---------------
C's rate is ( 1 job ) / ( 15 hrs )
C can do of the job in:
hrs to finish the work

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