SOLUTION: A man can mow his lawn in 4 hours. His son can do the job in 3 hours. If the son takes over an hour after his father, how long will it take him to finish mowing the lawn?

Question 1141930: A man can mow his lawn in 4 hours. His son can do the job in 3 hours. If the son takes over an hour after his father, how long will it take him to finish mowing the lawn?
Answer by VFBundy(438) (Show Source): You can put this solution on YOUR website!
Formula for work problems:
Rate of work * Time spent working = Portion of job completed

The man's rate of work is 1/4 of the job per hour, so after 1 hour of work:

1/4 job/hour * 1 hour worked = 1/4 of job completed.

This means 3/4 of the job remains when the son takes over.

The son's rate of work is 1/3 of the job per hour. We also know that he will complete the remaining 3/4 of the job. We are looking for how long it will take him.

1/3 job/hour * Hours worked (h) = 3/4

Put this into an equation and solve for h:

1/3 * h = 3/4

Multiply each side of the equation by 3:

h = 9/4

So, it will take the son 9/4 of an hour...or 2.25 hours...or 2 hours and 15 minutes...to finish mowing the lawn.
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