Bob and Dora Sweet wish to start investing $1,000 each month. The Sweets are looking at five investment plans and wish to maximize their expected return each month. Assume interest rates remain fixed and once their investment plan is selected they do not change their mind. The investment plans offered are:
Fidelity 9.1% return per year
Optima 16.1% return per year
CaseWay 7.3% return per year
Safeway 5.6% return per year
National 12.3% return per year

Since Optima and National are riskier, the Sweets want a limit of 30% per month of their total investments placed in these two investments. Since Safeway and Fidelity are low risk, they want at least 40% of their investment total placed in these investments.

What would be a recommended mixture of investment plans for Bob and Dora Sweet based on their requirements?