SOLUTION: An aluminum plate is made according to the following dimensions. The outer radius is 8 inches and the inner radius is 4 inches. (See diagram below) Use π = 3.14 as an approxim

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Question 380529: An aluminum plate is made according to the following dimensions. The outer radius is 8 inches and the inner radius is 4 inches. (See diagram below) Use π = 3.14 as an approximate value. (a) How many square inches in area is the aluminum plate (the shaded region)? (b) If the cost to construct the plate is $6.50 per square inch, what is the construction cost? (Area = ∏ r2 ).
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
The area of shaded portion = area of larger circle - area of smaller circle.
larger circle
radius = 8 "
Area = pi*8*8
area = 64 pi
...
Area of inner circle = pi*4*4
area = 16pi
..
difference = 64pi-16pi
=48pi
=48*3.14
=150.72 in^2 is the shaded area
..
1 in^2 = $6.50
150.72in^2= 150.72*6.50
=$ 979.68 is the cost
...
m.ananth@hotmail.ca