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Consider $\"\"$ is the amount placed in AAA bond and $\"\"$ is the amount placed in a CD. \ \

The total return is $\"\"$ . \ \

Hence $\"\"$ is the objective function to be maximized. \ \

The constraints are : \ \

A positive amount must be invested in each then $\"\"$ , $\"\"$ . \ \

Total investment cannot exceed then $\"\"$ . \ \

Investment in the CD must be atleast $\"\"$ then $\"\"$ . \ \

Investment in the CD must exceed or equal the investment in the bond. \ \

Graph : \ \

Graph the constraints . \ \

$\"\"$ \ \

Observe the graph the corner points are $\"\"$ , $\"\"$ , $\"\"$ , $\"\"$ and $\"\"$ . \ \

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The function is $\"\"$ .

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The maximum profit is $\"\"$ when $\"\"$ is invested in AAA bond and $\"\"$ is invested in a CD.

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The maximum profit is $\"\"$ when $\"\"$ is invested in AAA bond and $\"\"$ is invested in a CD.