SOLUTION: A thick-walled metal pipe of length 20 cm has an inside diameter of 2.0 cm and an outside diameter of 2.4 cm. What is the total surface area of the pipe, counting the ends in mete

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Question 896458: A thick-walled metal pipe of length 20 cm has an inside diameter of 2.0 cm and an outside diameter of 2.4 cm. What is the total surface area of the pipe, counting the ends in meters squared?
Answer: 279

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Look at the ends, first. Each end is based on a circle, and the area of the inner circle is absent.
OuterCircle-InnerCircle=EndArea for 1 end.

Inner Diameter, 2.0 cm, radius 1.0 cm.
Outer Diameter, 2.4 cm, radius 1.2 cm.

The pipe has TWO of these ends.
2%28pi%2A1.2%5E2-pi%2A1.0%5E2%29
2pi%281.2%5E2-1.0%5E2%29
0.88pi--------total of the ends.

Inner Surface: 20%2A%282%2A1%2Api%29=40pi
Outer Surface: 20%2A%282%2A1.2%2Api%29=48pi

ALL of surface area for this pipe:
%280.88%2B40%2B48%29%28pi%29 square centimeters.
highlight%2888.88%28pi%29%29 square centimeters.