Melinda invested three times as much money at 9% yearly interest as she did at 7%. her total yearly interest from the two investments was 170$ How much did she invest at each rate
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To solve this problem, let's start by assigning variables to the unknowns. Let's say Melinda invested x dollars at 7% interest and 3x dollars at 9% interest.
The interest earned from the first investment at 7% can be calculated by multiplying the amount invested (x) by the interest rate (7/100). This can be written as 0.07x.
Similarly, the interest earned from the second investment at 9% can be calculated by multiplying the amount invested (3x) by the interest rate (9/100). This can be written as 0.09(3x) or 0.27x.
According to the given information, the total yearly interest earned from both investments is $170. So, we can set up the equation:
0.07x + 0.27x = 170
Now, let's solve this equation to find the value of x.
Combining like terms, the equation becomes:
0.34x = 170
Divide both sides of the equation by 0.34 to isolate x:
x = 170 / 0.34
x ≈ 500
Now that we have the value of x, we can find the amount invested at each rate:
Melinda invested x dollars at 7%, which is approximately $500.
She invested 3x dollars at 9%, which is approximately 3 * $500 = $1500.
Therefore, Melinda invested $500 at 7% and $1500 at 9%.