The quality manager at a battery manufacturing company wants to determine if lithium-ion batteries have less variability in discharge time than nickel-cadmium batteries. Using products with similar power draws, he has measured the time until discharge (in hours) for random samples of 16 lithium-ion batteries and 26 nickelcadmium batteries. The sample variance of the discharge times is 0.44 hours2 for the lithium-ion batteries and 0.89 hours2 for the nickel-cadmium batteries.
a. State the appropriate hypotheses to test whether the variance in discharge time for the lithium-ion batteries is less than the nickel-cadmium batteries.
b. Compute the value of the test statistic. What assumption did you make?
c. Use Excel's F. DIST.RT function to calculate the p-value.
d. Make a conclusion at the 5% significance level.
e. Would your conclusion change at the 10% significance level?