George can mow his lawn in 3 hours, Al can mow his lawn in 5 hours. How long will it take both of them working together?

Guest Feb 29, 2020

#2**0 **

*George can mow his lawn in 3 hours, Al can mow his lawn in 5 hours. How long will it take both of them working together?*

We're assuming George's lawn and Al's lawn are the same size, to make

the rates consistent, and that they're working together on the same lawn.

George's rate of mowing is 1 lawn per 3 hours, which is 1/3 lawn/hour.

Al's rate of mowing is 1 lawn per 5 hours, which is 1/5 lawn/hour.

Working together means add the two rates 1/3 + 1/5 = combined rate of mowing

After finding common denominator 5/15 + 3/15 = 8/15 They can mow 8 lawns in 15 hours.

So 8/15 lawns per hour ... invert that amount to get the value in units of hours per lawn

15/8 hours per lawn, which when you do the division is 1**.**875 hrs/lawn,

or another way of saying it is: **one hour, fifty-two & a half minutes**.

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Guest Feb 29, 2020