Angela is buying her first home. She has saved $$60,000$ for a downpayment, intending to make a down payment of at least $20\%$ of the purchase price. Angela wants to make an offer on a home which is slightly over her budget at $$325,000.$ As she does not have any additional funds available to increase her downpayment, she needs to consider a high$-$ratio mortgage. Her lender explains that she will need to pay mortgage default insurance premiums, and that the premiums can be paid in cash or financed over the first mortgage term. He provides the following premium rate schedule:

Loan$-$to$-$Value Ratio Mortgage Default Insurance Premium

$($As a percentage of mortgage loan$)$

Up to $80\%2\mathrm{.}40\%$

Up to $85\%2\mathrm{.}80\%$

Up to $90\%3\mathrm{.}10\%$

Up to $95\%4\mathrm{.}00\%$

Angela is pre$-$approved for a mortgage with a $25-$year amortization period and an equivalent annual interest rate of $6\mathrm{.}39\%$ for a five$-$year term. Payments will be due at the end of each month. If Angela finances the mortgage default insurance premiums over her first mortgage term, what will the monthly insurance cost be$?$

$$50$

$$145$

$$178$