uestion $5$ Assume a $15$cm diameter wafer has a cost of $$1200,$ contains $84$ dies, and has

$0\mathrm{.}02$ defects$/$cm$2$ and a $20$cm diameter wafer has a cost of $$1500,$ contains $100$ dies and

$0\mathrm{.}031$ defects$/$cm$2.$ Find the cost per die for both wafers.

Which wafer has higher cost and why?