SOLUTION: sol can paint a house in 9 hours while ding can paint the same house in 16 hours. after 4 hours of working together, ding left and sol finish the job alone. How many hours did it t

Algebra ->  Rate-of-work-word-problems -> SOLUTION: sol can paint a house in 9 hours while ding can paint the same house in 16 hours. after 4 hours of working together, ding left and sol finish the job alone. How many hours did it t      Log On


   

Question 1008001: sol can paint a house in 9 hours while ding can paint the same house in 16 hours. after 4 hours of working together, ding left and sol finish the job alone. How many hours did it take sol to finish the job?
Found 2 solutions by josgarithmetic, dkppathak:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Sol's rate, 1%2F9
Dink's rate, 1%2F16%7D%0D%0ASol+and+Dink+Together%2C+%7B%7B%7B1%2F9%2B1%2F16.
Time for Sol to work alone to finish, t.

The rates are for JOBS per HOUR; the numerator shown in the individual rates is because
the time being connected to ONE job.

4 hours working together, amount of job was %281%2F9%2B1%2F16%29%2A4.

t hours Sol working to finish, alone, job was %281%2F9%29t.

1 job is how much of JOBS to do.
highlight%28%281%2F9%2B1%2F16%294%2B%281%2F9%29t=1%29

Solve for t.

Answer by dkppathak(439) About Me  (Show Source):
You can put this solution on YOUR website!
sol can paint a house in 9 hours while ding can paint the same house in 16 hours. after 4 hours of working together, ding left and sol finish the job alone. How many hours did it take sol to finish the job?
sol can pain a house in 9 hrs
ding can paint a house in 16 hrs
sol 1 hrs painting =1/9 parts
ding 1 hrs painting =1/16 parts
ding and sol 1 hrs together =1/9+1/16=25/144 parts
working together for 4 hrs =4x25/144=25/36 parts
reaming part=1-25/36=11/36 parts
sol will finish work=11x9/36=11/4 days