Answer:
to earn a $7180 annual income from the investments, the bank needs to invest $10,000 into the bonds.
Step-by-step explanation:
Let the mortgage investment be X
The Bond to be Y
and the CDs to be Z
Thus;
X+Y+Z = 86000 ------- (1)
Y + Z = X ------------(2)
10X + 9Y + 6Z = 7180 × 100 ------ (3)
So;we now have:
X+Y+Z = 86000 ------- (1)
Y + Z = X ------------(2)
10X + 9Y + 6Z = 718000 ------ (3)
Let ; replace X with Y+Z in equation (1) and (3)
Y+Z + Y+Z = 86000
2Y + 2Z = 86000
Divide both sides by 2
Y+Z = 43000 ------ (4)
From equation (3)
10X + 9Y + 6Z = 718000
10(Y+Z) + 9Y + 6Z = 718000
10Y +10Z + 9Y +6Z = 718000
19Y + 16Z = 718000 -----(5)
Y+Z = 43000 ------ (4)
19Y + 16Z = 718000 -----(5)
Using elimination method; multiply (-16) with equation (4) and (5) ; so, we have:
-16 Y -16 Z = -688000
<u> 19Y + 16Z = 718000 </u>
<u> 3Y + 0 = 30000 </u>
<u />
3Y = 30000
Y = 30000/3
Y = 10000
From (4);
Y+Z = 43000
So; replace Y with 10000; we have:
10000 + Z = 43000
Z = 43000 - 10000
Z = 33000
From (1) ;
X+Y+Z = 86000
X + 10000 + 33000 = 86000
X + 43000 = 86000
X = 86000 - 43000
X = 43000
Since we assume the bond to be Y and Y = $10000;
Thus; to earn a $7180 annual income from the investments, the bank needs to invest $10,000 into the bonds.
