Ms$.$ Speculator sold short $15,000$ shares of TPHB on October $1,2019$ at $$36\mathrm{.}50,$ and covered her position

on February $14,2020,$ at $$21\mathrm{.}25.$

a$.$ How much money did Ms$.$ Speculator need to deposit to her margin account on October $1?$

$$273,750$

b$.$ How much money did Ms$.$ Speculator make? What was her rate of return on the investment?

$$228,750$; $83\mathrm{.}56\%$

initial$/$maintenance margins are $50\%/40\%$

$(150\%/130\%$ for short sales$)$