A retired couple have up to $30,000 to invest in fixed-income securities.
Their broker recommends investing in two bonds: one a AAA bond yielding 8%; the other a Upper B Superscript plus B+ bond paying 12%.
After some consideration, the couple decide to invest at most ?$12,000 in the Upper B Superscript plus B-rated bond and at least? $6000 in the AAA bond.
They also want the amount invested in the AAA bond to exceed or equal the amount invested in the Upper B Superscript plusB+ bond.
What should the broker recommend if the couple (quite naturally) want to maximize the return on their investment?