Question 763466
1) Radius of washer = 2cm.
Area of washer = Pi*radius^2
               = Pi * 2^2
               = Pi * 4
               = 12.57cm^2
  Radius of hole = 1cm
Area of hole = Pi*r^2
             = Pi*1^2
             = Pi * 1
             = 3.14cm^2
12.57cm^2 - 3.14cm^2 = 9.43cm^2 of metal
50 * 9.43cm^2 = 471.5cm^2 of metal.
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2) Radius of pool + walkway = 20 feet
Area of pool + walkway = Pi * r^2
                       = Pi * 20^2
                       = Pi * 400
                       = 1256.64 feet^2
  Radius of pool = 17 feet
Area of pool = Pi * r^2
             = Pi * 17^2
             = Pi * 289
             = 907.92 feet^2
Area of (pool + walkway) - pool
           1256.64 feet^2 - 907.92 feet^2
                = 348.72 feet^2 (the area of the walk.)