A loan officer compares the interest rates for 48-month fixed-rate auto loans and 48-month variable-rate auto loans. Two independent, random samples of auto loan rates are selected. A sample of five 48-month variable-rate auto loans had the following loan rates: 2. 40% 3. 118 2.8768 3. 218 3. 178 while a sample of five 48-month fixed-rate auto loans had loan rates as follows: 4.0384 3.868 4.378% 3. 828 4. 218 Figure 11.7 JMP Output of Testing the Equality of Mean Loan Rates for Variable and Fixed 48-Month Auto Loans Means and Std Deviations Level Number Mean Std Dev Fixed 4. 06120 0. 335233 Variable 5 2. 95320 0. 235426 t Test Variable-Fixed Assuming equal variances Difference -1. 1080 t Ratio -6 . 04812 Std Err Dif 0.1832 DF 8 Upper CL Dif -0. 6855 prob > t 0. 0003* Lower CL Dif -1. 5305 Prob > 0. 9998 Confidence ). 9 prob