In order to compare the durability of four different brands of golf balls (Alpha, Best, Century, and Divot), the National Golf Association randomly selects balls of each brand and places each ball into a machine that exerts the force produced by a 250 yard drive. The number of simulated drives needed to crack or chip each ball is recorded. Use a significance level of 0.05 to conduct all hypothesis tests and construct confidence intervals.

Analysis of Variance

SourceDFSum of SquaresMean SquareFRatioProb > F

Brand338504.15012834.721.1742<.0001*

Error169698.400606.1

C. Total1948202.550

What is the value of the between-treatment variability

606.1

48202.55

21.1742

38504.150

9698.4