SOLUTION: Peter can mow his lawn in 6 minutes. Peter's son can mow it in 8 minutes. How long will it take them to do it together?

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Question 721591: Peter can mow his lawn in 6 minutes. Peter's son can mow it in 8 minutes. How long will it take them to do it together?
Answer by fcabanski(1391) About Me  (Show Source):
You can put this solution on YOUR website!
Work problems are like distance problems.


D = rate x time in Distance problems, and W = rate x time in work problems. The Work is generally 1, the whole job.


For Peter the formula is 1 (lawn mowed) = 1/6 lawn per minute x 6 minutes.


For the son the formula is 1 = 1/8 * 8.


Add their rates together, 1/8 + 1/6 = 3/24 + 4/24 = 7/24.


The equation for their rate working together is 1 = 7/24 * t


Divide both sides by 7/24 to find t. t = 1 / 7/24 = 1 * 24/7 = 24/7 = 3 and 3/7 minutes = approx. 3 minutes 26 seconds.

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