If it takes Polly 20 minutes to paint a fence that is 3 feet

If it takes Polly 20 minutes to paint a fence that is 3 feet tall and 10 feet long. How long will it take her to paint a fence that is 6 feet tall and 20 feet long. Assuming she continues at the same rate?

Solution

Area of fence- (length*width)

=3*20

= 60feet square

60 feet square takes 20 minutes

Now the new area of fence-= 6*20

=120 feet square

As we know rate is same so rate = (20÷60) minutes per feet square

So 120 feet square will take time = (20÷60)*120

=40 minutes