In Exercise 20 "Blanking Out on Tests," using the "smaller of n1 - 1 and n2 - 1" for the number of degrees of freedom results in df = 15. Find the number of degrees of freedom using Formula 9-1. In general, how are hypothesis tests and confidence intervals affected by using Formula 9-1 instead of the "smaller of n1 - 1 and n2 - 1"?

PEPSREG VOL PESDETM PPDEVOL PEPSI REGT COKE DIET VOL 12.1 12.1 COKE DIET WT 0.7773 0.7758 0.7896 0.7868 0.7844 COKE REG WT COKE REGVOL 12.2 0.8156 12.1 12.2 0.7846 12.2 0.7938 0.8170 0.8211 12.2 12.2