SOLUTION: A mechanic requires 3 h to repair a transmission, whereas an apprentice requires 9 h to make the same repairs. The mechanic worked alone for 1.5 h and then stopped. how long wil

Question 379528: A mechanic requires 3 h to repair a transmission, whereas an apprentice requires 9 h to make the same repairs. The mechanic worked alone for 1.5 h and then stopped.
how long will it take the apprentice, working alone, to complete the repairs?
Answer by ptaylor(2198) (Show Source): You can put this solution on YOUR website!
Let x=amount of time it takes the apprentice, working alone, to complete the repairs
The mechanic works at the rate of 1/3 transmission per hour
The apprentice works at the rate of 1/9 transmission per hour
In 1.5 hours, the mechanic completes (1/3)*1.5 or 1/2 of the job, leaving 1/2 of the job yet to be done. So we have to calculate the following:
(1/9 transmission per hour)* x hours=(1/2 transmission); or
(1/9)x=1/2 multiply each side by 18
2x=9
x=4.5 hours---time required for the apprentice to finish the job
Hope this helps---ptaylor
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