=+41. Modern interest rates. In Exercise 39 you investigated the federal rate on 3-month Treasury bills between 1950 and M16_SHAR8696_03_SE_C16.indd 576 14/07/14 7:38 AM Exercises 577 1980. The scatterplot below shows that the trend changed dramatically after 1980, so we’ve built a new regression model that includes only the data since 1980 (from x = 30 and on in the plot below).

3 6

9 12 30.0 37.5 45.0 52.5 60.0 Years since 1950 Rate (%)

Dependent variable is: Rate R-squared = 78.3% s = 1.644 Variable Coeff Intercept 19.2024 Year-50 -0.30871