A piece of triangle-shape plastic is produced. Then, a circle is cut out from the middle, as shown in the following gure. Assume that the length of base and height of the triangle, and radius of the hole are independent with mean and variance given in the following table. Area of triangle = Height X Base/2 Area of Circle = at X (Radius)2, where rt=3. 14 _-_ (a) Estimate the mean of the area of the plastic piece. (9 points) (b) Estimate the variance of the area of the plastic piece. (13 points)