$21\mathrm{.}4$ How much money do you need to deposit in a bank each month if you are planning to have $$5000$ in four years by the time you get out of college? The bank offers a $6\mathrm{.}75\%$ interest rate that compounds monthly.

$21\mathrm{.}5$ Determine the effective rate corresponding to the following nominal rates:

a$.6\mathrm{.}25\%$ compounding monthly

b$.9\mathrm{.}25\%$ compounding monthly

c$.16\mathrm{.}9\%$ compounding monthly

$21\mathrm{.}6$ Using Excel or a spreadsheet of your choice, create interest$-$time factor tables, similar to Table $21\mathrm{.}9,$ for $i=6\mathrm{.}5\%$ and $i=6\mathrm{.}75\%.$