Bunuel
James can complete a job in 6 hours and Sarah can complete the same job in 4 1/2 hours. If James works on the job alone for a certain amount of time and Sarah works on the job alone for half as long as James, and it takes 1 hour for them to complete the remainder of the job together, how long did James work on the job alone?
A. 1 hour, 6 minutes
B. 1 hour, 10 minutes
C. 2 hours, 12 minutes
D. 2 hours, 20 minutes
E. 3 hours, 18 minutes
The rate of James is 1/6 and the rate of Sarah is 1/4.5 = 10/45 = 2/9.
We can let the time James works = t and the time Sarah works = t/2. Thus, we can create the equation, which represents James working to t hours and 1 hour and Sarah working for t/2 and 1 hour:
1/6 + 2/9 + t/6 + (2/9 * t/2) = 1
1/6 + 2/9 + t/6 + t/9 = 1
Multiplying by 18, we have:
3 + 4 + 3t + 2t = 18
5t = 11
t = 11/5 = 2 1/5 hours = 2 hours and 12 minutes.
Answer: C