Answer:
They should invest $40,000 in stable bonds and $60,000 in volatile bonds. Their maximum income is $129,900
Step-by-step explanation:
Let us assume that, they invested x in stable bonds and y in volatile bonds.
The Fiedler family has up to $130,000 to invest.
[tex]x+y\le130000[/tex]
They decide that they want to have at least $40,000 invested in stable bonds.
[tex]x\ge40000[/tex]
They decide that they want no more than $60,000 should be invested in more volatile bonds.
[tex]y\le60000[/tex]
The amount in the stable bond should not exceed the amount in the more volatile bond, so
[tex]x\le y[/tex]
As we have to find maximum income from stable bonds yielding 5.5% and volatile bonds yielding 11%, so we have to maximize [tex]1.055x+1.11y[/tex]
Here,
Max [tex]1.055x+1.11y[/tex]
[tex]x+y\le130000[/tex]
[tex]x\le y[/tex]
[tex]x\ge40000[/tex]
[tex]y\le60000[/tex]
Using LPP, plotting the inequalities on graph, we get the feasible region as shown in the attachment.
The solutions to the system are,
[tex](40000,60000),(40000,40000),(60000,60000)[/tex]
Now putting all the solutions in the objective function to find the maximize the function.
[tex]f(40000,60000)=1.055(40000)+1.11(60000)=\$108800[/tex]
[tex]f(40000,40000)=1.055(40000)+1.11(40000)=\$86600[/tex]
[tex]f(40000,60000)=1.055(40000)+1.11(60000)=\$129900[/tex]