please answer q $2$:

$1.$ Your nephew, Caleb, is $25$ years old and has decided to start a retirement program. Beginning in exactly one month he will contribute the amount of $$1300$ every month into a retirement account. $80\%$ of the funds will be invested in a high$-$yield equity fund that is expected to earn $8\%$ annually; $20\%$ of the contribution will be invested in a lower$-$yield bond fund that is expected to return $5\%$ annually. He will continue to make contributions for the next $40$ consecutive years. When he retires, he will combine his money into an account with an annual return of $2\%.$ Assuming he lives another $25$ years, what is the maximum amount he will be able to withdrawal per month upon retirement?

Answer to q$1$:

Future value of Contributions

High$-$yield equity fund contributions

Monthly contribution $1040$

Annual interest rate $8\%$

Monthly interest rate $0\mathrm{.}006667$

n $480$

FV of annuity $$3,491\mathrm{.}01$

$$3,630,648\mathrm{.}14$

Lower$-$yield bond fund contributions

Monthly contribution $260$

Annual interest rate $5\%$

Monthly interest rate $0\mathrm{.}004167$

n $480$

FV $1526\mathrm{.}02015642078000$

$$396,765\mathrm{.}24$

Total future value

FV total $$4,027,413\mathrm{.}39$After retirement, Caleb combines his funds into an account with an annual return of $2\%$

Present value of annuity PMT$+(1-(1+$r$)^-$n$)/$r$)$

PMT PV$*($r$/((1-(1+$r$)^-$n$)$

PMT $0\mathrm{.}863763484017273$

$$0\mathrm{.}01$

Monthly withdrawal $($PMT$)=$ $$31,084\mathrm{.}23$

Q$2($please answer this$)$:

What if Caleb$$s assumptions are incorrect. Instead of his stock fund earning $8\%$ annually, the fund only returns $7\mathrm{.}5\%$ for the investment period. Using this new assumption $($but keeping all other assumptions the same$),$ what is the maximum amount he will be able to withdrawal per month upon retirement?

What other factors may affect the Caleb$$s ability to retire in $40$ years?