SOLUTION: Marie and Isabel can paint an apartment in 5hours working together. If Marie can do the same job alone in 7hours, how long will it take Isabel to finish it alone?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Marie and Isabel can paint an apartment in 5hours working together. If Marie can do the same job alone in 7hours, how long will it take Isabel to finish it alone?      Log On


   

Question 8333: Marie and Isabel can paint an apartment in 5hours working together. If Marie can do the same job alone in 7hours, how long will it take Isabel to finish it alone?
Answer by srinivas123(23) About Me  (Show Source):
You can put this solution on YOUR website!
Marie and Isabel can paint an apartment in 5hours working together. If Marie can do the same job alone in 7hours, how long will it take Isabel to finish it alone?
Given,if they work together then the time taken is 5 hours.
If Marie only works then it takes 7 hours.
So the work done by marie will be 1/7.
Work done by both in one hour is 1/5
let the time taken by Isabel be x , so work the work done by him in one hour will be 1/x.
so,
1/x + 1/7 = 1/5
solving this equation we get ,
x= 8.5 hours or 8 hours and 30 mins.
Isabel will take 8 hours and 30 mins if he does it lonely.