SOLUTION: bill does a certain job in half the time harry does the same job. when they work together on the same job it takes six hours and forty minutes. how long does it take harry to do th

Algebra ->  Rate-of-work-word-problems -> SOLUTION: bill does a certain job in half the time harry does the same job. when they work together on the same job it takes six hours and forty minutes. how long does it take harry to do th      Log On


   

Question 932182: bill does a certain job in half the time harry does the same job. when they work together on the same job it takes six hours and forty minutes. how long does it take harry to do the job by himself
Answer by ptaylor(2198) About Me  (Show Source):
You can put this solution on YOUR website!
Note: 6hr and 40 min=6 2/3 hr=20/3 hr
Working together they work at the rate of 1/(20/3)=3/20 of the job/hr
Let x=amount of time needed for Bill to do the job
Bill works at the rate of 1/x of the job/hr
Then 2x=amount of time needed for Harry to do the job
Harry works at the rate of 1/2x of the job/hr
Our equation to solve is:
1/x + 1/2x = 3/20 multiply each term by 20x
20+10=3x
3x=30
x=10 hr--- amount of time needed for Bill to do the job
2x=20 hr---amount of time needed for Harry to do the job
CK
(1/10)(20/3)+(1/20)(20/3) has to equal 1 (1 job, that is)
(2/3)+(1/3)=1
1=1
Hope this helps----ptaylor