Question 31304
Let "x" be amount invested in corporate bonds at 10%
Then "x+3000" is amount invested in treas. bills at 5%
And "20000-(x+x+3000)"="17000-2x" is amount invested in treas. bonds at 7%
EQUATION:
interest + interest+ interest= 1390
0.10x + 0.05(x+3000)+0.07(17000-2x)=1390
10x+5(x+3000)+7(17000-2x)=139000
10x+5x+15000+119000-14x=139000
x=5000 (amount invested at 10% in corporate bonds
x+3000=8000 (amount invested at 5% in treas. bills
17000-2x=17000-10000=7000 (amount invested at 7% in treas. bonds.
Cheers,
Stan H.