$4.$ Consider the following two investment alternatives: First, a risky portfolio that pays a $20\%$ rate of return with a probability of $60\%$ or a $5\%$ rate of return with a probability of $40\%.$ Second, a Treasury bill that pays $6\%.$ If you invest $$50,000$ in the risky portfolio, your expected profit after one year would be $\_\_\_\_\_\_\_\_\_\_.(1$ points$)$

a$.$ $$3,000$

b$.$ $$7,000$

c$.$ $$7,500$

d$.$ $$10,000$