SOLUTION: Roma can finish weeding a flower in 4 1/2 hour. Roma has worked for 2 hours before Amor joined her and they finished the job in 2 hours. How long woild it take both of them to fini

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Roma can finish weeding a flower in 4 1/2 hour. Roma has worked for 2 hours before Amor joined her and they finished the job in 2 hours. How long woild it take both of them to fini      Log On


   

Question 330805: Roma can finish weeding a flower in 4 1/2 hour. Roma has worked for 2 hours before Amor joined her and they finished the job in 2 hours. How long woild it take both of them to finish the job working together? How long would it take Amor to do the job alone?
Answer by galactus(183) About Me  (Show Source):
You can put this solution on YOUR website!
Remember, fraction of work = (rate/unit)(number of units)
Roma's rate is 9/2 hours to complete a job. That means she finishes
1/(9/2)=2/9 of the job per hour (rate/unit). Thus, in 2 hours (number of units), she completes 2(2/9)=4/9 of the job.
Therefore, there is 5/9 of the job to complete after Amor joins in.
%282%2F9%2B1%2Ft%29%2A2=5%2F9
t=18 hours for Amor to complete the job alone.
So, they both can complete it together from beginning to end in
2%2F9%2B1%2F18=1%2Ft
t=18%2F5=3.6 hours working together.