$1.$ The amount paid after four years for a loan of $25,000$ at an annual rate of $5\mathrm{.}7\%$ compounded quarterly, if the final payment includes both principal and interest.

$2.$ The effective annual rate for an investment which pays interest monthly at an annual nominal rate of $5\%.$

$3.$ The required investment now if you want to collect $75,000$ after ten years and can invest at an annual rate of $3\mathrm{.}5\%$ compounded continuously.

$4.$ The amount of interest paid monthly on a $19,000$ loan that charges an interest rate of $6\mathrm{.}9\%$ p$.$a$.,$ assuming simple interest.

$5.$ The payback period for an investment with the following cash flows from years zero to six: $-1800$; $300$; $700$; $700$; $700$; $500.$

$6.$ The value today of a $4-$year monthly annuity of $790,$ if the interest rate received is $4\%$ p$.$a$.$