$1.$ Compute the interest paid on a $30-$year mortgage for $$305,944$ if the annual interest rate is $4\mathrm{.}9\%.$

$2.$ Brad and Sam$$take a $30-$year mortgage for a house that costs $$106,583.$ Assume the following:

$*$ The annual interest rate on the mortgage is $3\mathrm{.}5\%.$

$*$ The bank requires a minimum down payment of $11\%$ of the cost of the house.

$*$ The annual property tax is $1\mathrm{.}7\%$ of the cost of the house.

$*$ The annual homeowner's insurance is $$795.$

$*$ There is no PMI.

If they make the minimum down payment, what will their monthly PITI be$?$

$3.$ Suppose you take a $15-$year mortgage for a house that costs $$228,940.$ Assume the following:

$*$ The annual interest rate on the mortgage is $4\mathrm{.}3\%.$

$*$ The bank requires a minimum$$down payment$$of $7\%$ of the cost of the house.

$*$ The annual property tax is $1\mathrm{.}3\%$ of the cost of the house.

$*$ The annual homeowner's insurance is $$554.$

$*$ The monthly PMI is $$94.$

If you make the minimum down payment, what is the minimum gross monthly$$salary you must earn in order to satisfy the$28\%$ rule?