SOLUTION: Christopher can paint the interior of his house in 15 hours. If he hires Cynthia to help him, they can do the same job together in 9 hours. If he lets Cynthia work alone, how long
Algebra ->
Rate-of-work-word-problems
-> SOLUTION: Christopher can paint the interior of his house in 15 hours. If he hires Cynthia to help him, they can do the same job together in 9 hours. If he lets Cynthia work alone, how long
Log On
Question 630704: Christopher can paint the interior of his house in 15 hours. If he hires Cynthia to help him, they can do the same job together in 9 hours. If he lets Cynthia work alone, how long will it take her to paint the interior of his house? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! Christopher can paint the interior of his house in 15 hours.
If he hires Cynthia to help him, they can do the same job together in 9 hours.
If he lets Cynthia work alone, how long will it take her to paint the interior of his house?
:
Let c = time required by Cynthia alone
let the completed job = 1 (a painted house)
:
Each will do a fraction of the job. The two fractions add up to one.
:
A shared work equation + = 1
Reduce fraction + = 1
Multiply by 5c, resulting in:
3c + 5(9) = 5c
45 = 5c - 3c
45 = 2c
c = 45/2
c = 22.5 hrs, Cynthia alone
:
:
Check this on a calc
9/15 + 9/22.5 =
.6 + .4 = 1
