Final answer:
To calculate the decrease in interest rates over the next 32 years, we multiply the highest rate by 69% (0.69), which gives us 14.49%. The interest rate in 2013 was 6.51%.
Step-by-step explanation:
To find the interest rate in 2013, we start with the highest interest rate in 1981, which was 21%.
To calculate the decrease in interest rates over the next 32 years, we multiply the highest rate by 69% (0.69), which gives us 14.49%.
We then subtract this amount from the highest rate to find the rate in 2013.
21% - 14.49% = 6.51%
Therefore, the interest rate in 2013 was 6.51%.