A unit trust fund has a prospective average annual return of $7\mathrm{.}5\%$ over the next $15$ years. Estimate the value of a TZS $1,000,000$ investment after $25$ years when the returns are:$($a$)$ tax$-$free, $[6$ Marks$]($b$)$ subject to a deferred tax $($i$.$e$.$ taxed at the end of the $25$ years$)$ of $20\%($c$)$ subject to an annual tax of $20\%$