SOLUTION: A circular garden has a radius of 16 feet. You want to lay a concrete sidewalk 2 feet wide around the entire garden. If the walk will be 3 inches thick, how many yards of concrete

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Question 958499: A circular garden has a radius of 16 feet. You want to lay a concrete sidewalk 2 feet wide around the entire garden. If the walk will be 3 inches thick, how many yards of concrete will you need to order?
Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
inside walk radius=r=16 ft=5.33yd; outside walk radius=R=18ft=6yds
A=Area of walk=(area of outside circle)-(area of inside circle)
A=%28%28pi%29R%5E2%29-%28%28pi%29r%5E2%29
A=%28pi%29%286yds%29%5E2-%28pi%29%285.3yds%29%5E2
A=36%28pi%29yd%5E2-28.4%28pi%29yd%5E2
A=7.6%28pi%29yd%5E2=23.7yd%5E2
Area x Thickness will give volume Thickness=0.083yds
Volume=%2823.74yd%5E2%29%280.083yd%29=1.99yd%5E3
ANSWER: You will need 1.99 yards of concrete for the walk.