The times (in seconds) for loading, swinging, dumping, and returning for a shovel moving sandstone on a dam project were measured as shown in table at top of p. 24. Compute sample mean, variance, and coefficient of variation of each set of data. If the variability in total time is causing hauling problems, which operation should be studied as the primary source of variability in the total? Which of the summary statistics would be most useful in such a study?
