Mr. Jones has $14,000 to invest. He invests part at 7% and the rest at 11%. If he earns $1,220 in interest after
1 year, how much did he invest at each rate?
If there are $x at 7% then the rest (14000-x) is at 11%. So, adding up the interest, you have
.07x + .11(14000-x) = 1220
To solve this problem, we can use a system of equations. Let's assume Mr. Jones invested x dollars at 7% and (14,000 - x) dollars at 11%.
The interest earned from the 7% investment can be calculated as (x * 7%) = 0.07x.
The interest earned from the 11% investment can be calculated as ((14,000 - x) * 11%) = 0.11(14,000 - x).
According to the problem, the total interest earned is $1,220. So we can write the equation: 0.07x + 0.11(14,000 - x) = 1,220.
We can now solve this equation to find the value of x.
0.07x + 0.11(14,000 - x) = 1,220
0.07x + 1,540 - 0.11x = 1,220
-0.04x = -320
x = -320 / (-0.04)
x = $8,000
Mr. Jones invested $8,000 at 7% and the remaining amount, which is $14,000 - $8,000 = $6,000, at 11%.