First we need to find the area of the circle. The formula for the area of a circle is r^2 x pi = area
The radius is half of the diameter.
1.5^2 x 3.14 = area
2.25 x 3.14 = area
7.065 = area. Now that we have the area, we need to multiply that by how much the manhole cover weighs per square foot. So just multiply 7.065 by 8.2 and we get 57.93. Rounded up that equals 58. Hope that helps! :)