Math Problem Statement

investments. Part of the money is invested in a savings account with an annual rate of interest of 6%, part in. 7% annual yield bonds, and the remainder in a business. In 2006, when he lost 6% of the money that he invested in that business, his net income from all three investments was 660. If he invested 3000 more in the business than in the savings account, how much was through matrix method

Solution

Let's set up the problem and solve it using a system of linear equations and then apply the matrix method to find the solution.

Step 1: Define the Variables

Let:

  • xx = amount invested in the savings account (6% interest)
  • yy = amount invested in the bonds (7% interest)
  • zz = amount invested in the business (lost 6% in 2006)

Step 2: Translate the Problem into Equations

  1. Interest Income Equation: The total income from all three investments in 2006 was $660. Thus, 0.06x+0.07y0.06z=6600.06x + 0.07y - 0.06z = 660

  2. Business Investment Relation: The amount invested in the business was $3000 more than in the savings account, so: z=x+3000z = x + 3000

  3. Total Investment Relation: We need another equation involving xx, yy, and zz to solve for the exact amounts. Since no total investment amount is given, we assume a system where these two main relationships are solved independently, as the third relation isn't provided.

Step 3: Substitute and Set Up Equations in Matrix Form

Using z=x+3000z = x + 3000 in the first equation, we get: 0.06x+0.07y0.06(x+3000)=6600.06x + 0.07y - 0.06(x + 3000) = 660 Simplify this equation: 0.06x+0.07y0.06x180=6600.06x + 0.07y - 0.06x - 180 = 660 0.07y=8400.07y = 840 So: y=8400.07=12000y = \frac{840}{0.07} = 12000

Now, substitute y=12000y = 12000 back to find xx and zz:

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Systems of Equations
Matrix Method

Formulas

Income equation: 0.06x + 0.07y - 0.06z = 660
Business investment relation: z = x + 3000

Theorems

Matrix solution method for linear systems

Suitable Grade Level

Grades 11-12