Cosette will retire in $35$ years. To that end she contributes $$900$ per month to her $401-$k account during the first $20-$years, then stops her contributions and lets the funds

compound for the next $15$ years. How much would her account hold at retirement if she earned an annual rate of $11\mathrm{.}5\%$ monthly compounded?

$$4,634,711\mathrm{.}68$

$$5,597,983\mathrm{.}04$

$$2,999,789\mathrm{.}12$

$$4,425,537\mathrm{.}6.$