On January 1, 2011, Maria invested $1,000 at 6 percent interest per year for three years (with yearly capitalization). The CPI stood at 100 in January 1, 2011. At year later it climbed to 105 and on January 1, 2013 was 110, and on January 1, 2014, the day Marias investment matured, the CPI was at 120. Find the real interest rate that Maria's total real return over the 3-year period. (Write your answer without the %. If your answer is XX.yy%, write XX.y, only two decimal points.)

To calculate the real interest rate, we first need to calculate the nominal return and then adjust it for inflation.

Step 1: Calculate the nominal return Maria invested $1,000 at 6 percent interest per year for three years. This means each year, her investment grows by 6 percent.

After the first year, her investment is worth $1,000 * 1.06 =$1,060. After the second year, her investment is worth $1,060 * 1.06 =$1,123.60. After the third year, her investment is worth $1,123.60 * 1.06 =$1,190.22.

So, the nominal return on her investment over the three years is ($1,190.22 -$1,000) / $1,000 = 0.19022 or 19.022%.

Step 2: Adjust for inflation The Consumer Price Index (CPI) measures the average change over time in the prices paid by urban consumers for a market basket of consumer goods and services. We can use the CPI to adjust Maria's return for inflation.

The CPI was 100 when Maria made her investment and 120 when her investment matured. This means the price level increased by (120 - 100) / 100 = 0.20 or 20% over the three years.

Step 3: Calculate the real return The real return is the nominal return adjusted for inflation. We can calculate it using the formula:

Real return = (1 + nominal return) / (1 + inflation rate) - 1

Substituting the values we have:

Real return = (1 + 0.19022) / (1 + 0.20) - 1 = 0.1585 or 15.85%.

So, the real interest rate that Maria's total real return over the 3-year period is 15.85%.