An adverse market delivery charge rate depends on the credit score of the borrower, the amount borrowed, and the loan$-$to$-$value $($LTV$)$ ratio. The LTV ratio is the ratio of amount borrowed to appraised value of the home. For example, a homebuyer who wishes to borrow $$250,000$ with a credit score of $730$ and an LTV ratio of $80\%$ will pay $0\mathrm{.}75\%(0\mathrm{.}0075)$ of $$250,000$ or $$1875.$ The table below shows the adverse delivery charge for various credit scores and an LTV ratio of $80\%.$ Answer parts $($a$)$ through $($c$).$

$\backslash$table$[[$Credit Score,Charge Rate$],[659,3\mathrm{.}5\%$