Mr$.$ Tran has $$22,500$ to invest, some in bonds and the rest in stocks. He has decided that the money invested in bonds must be at least twice as much as that in stocks. But the money invested in bonds must not be greater than $$16,300.$ If the bonds earn $4\%,$ and the stocks earn $9\%,$ how much money should he invest in each to maximize his interest earned?

a$.$ Of the options below, give the number that represents

the correct set of variables

the correct objective function description $?,$

the correct set of constraint descriptions $?v.$

total interest earned on the investments

the amount of money invested in bonds and stocks

the length of the life of the bonds

the amount of money available to invest and the restrictions imposed on each investment

b$.$ Letting $x$ be the first of the variables listed in the problem statement, and $y$ the second, write the objective function.

$z=$

c$.$ Graph the feasible region on paper, then list the comer points of the feasible region.

$($Enter ordered pairs $(x,y),$ separated by commas.$)$

d$.$ Test the corner points to find the optimum value of the objective function:

The "winning" corner point is

The optimum value of the objective function is