4 identical momento is made by a school to award 4 students for four values - Honesty, Punctuality, Cleanliness and Non-Violence. The shape of the momento is as shown in the figure. The base PQRS is silver plated from the front side at the rate of $\$10\; per \;cm^2$. What is the total cost of the silver plating ? (Take $\pi=\frac{22}{7}$)

Question

$\begin{array}{1 1} (a)\; \$400 \\ (b)\; \$420 \\ (c)\; \$460 \\ (d)\;\$500 \end{array}$