Question

Collectible coins are sometimes plated with gold to enhance their beauty and value. Consider a commemorative quarter-dollar advertised for sale at $4.98. It has a diameter of 24.3 mm, a thickness of 1.78 mm, and is completely covered with a layer of pure gold 0.154 µm thick. The volume of the plating is equal to the thickness of the layer multiplied by the area to which it is applied. The patterns on the faces of the coin and the grooves on its edge have a negligible effect on its area. Assume the price of gold is $15.5 per gram.

(a) Find the cost of the gold added to the coin.

Answer 1