Inequality word problem?

[cmorton557]

Christine is planning to invest a total of $21,000 in two accounts. If she invests $13,000 in a CD paying 12% annual simple interest, at what rate does the remainder of her money need to be invested so that the two investments together yield at least $2520 in yearly simple interest? (Set up and solve an inequality to answer this question).

[shyamjayakannan]

We know that [tex]I=PRT\Rightarrow I=P_1R_1T+P_2R_2T[/tex]. Since we want at least 2520, [tex]P_1R_1T+P_2R_2T\ge2520\Rightarrow13000\times0.12+8000R_2\ge2520[/tex] because [tex]T=1[/tex]

So, [tex]8000R_2\ge960\Rightarrow\boxed{R_2\ge0.12}[/tex]