Refer to the railway repair time data in Exercise 16. Carry out a test at significance level .01 to see whether the population standard deviation for time-to-repair is larger for high rail breaks than for low rail breaks.

Data From Exercise 16

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The accompanying time-to-repair (min) data for both high rail and low rail breaks on curved track appeared in the article "Uncertainty Estimation in Railway Track Life-Cycle Cost" (J. Rail Rapid Transit 2009: 285-293). (On a curved track, the high rail is the outer rail with the larger radius, while the low rail is the inner rail with the smaller radius.) High: 159 120 480 149 270 547 340 43 228 202 240 218 Low: 258 154 216 240 169 75 340 202 202 216 Normal probability plots of both samples show reasonably linear patterns.