SOLUTION: hi Please help Mike can finish a job in 5 hours. After working for 20 minutes, he requested Ronald to work with him and the two finished the job in 3 hours. How long would it t

Algebra ->  Rate-of-work-word-problems -> SOLUTION: hi Please help Mike can finish a job in 5 hours. After working for 20 minutes, he requested Ronald to work with him and the two finished the job in 3 hours. How long would it t      Log On


   

Question 997060: hi Please help
Mike can finish a job in 5 hours. After working for 20 minutes, he requested Ronald to work with him and the two finished the job in 3 hours. How long would it take Ronald alone to finish the same job?
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
Ronald's rate is unknown. He needs some r hours to do 1 job if he works alone. Say his rate is 1%2Fr.

Mike's rate is 1%2F5 jobs per hour. He only worked alone for 1%2F3 hour, which is twenty minutes, before getting help from Ronald.
Both together worked for 3 hours.





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A better choice than the variable, r, might have been. Reminder: I assigned r as the TIME for Ronald to do 1 job if he works alone. Ronald's work rate is therefore 1%2Fr in unit of JOB per HOUR. A better variable choice might have been x, or t, or y; but I chose r, to stand for the time for RONALD to do 1 job himself. According to the variable assignment and the formulated equation, when you solve for r, this will be how many hours that Ronald needs to do 1 job if he works alone.