Question: Z Score for Old Faithful – Eruptions of the Old Faithful geyser have duration times with a mean of 245.0 sec and a standard deviation of 36.4 sec (based on Data Set 15 in Appendix B) One eruption had a duration time of 110 seconds.

A. What is the difference between a duration time of 110 sec and the mean?

B. How many standard deviations is that (the difference the difference found in part (a))?

C. Convert the duration time of 110 sec to a Z score.

D. If we consider ‘usual’ duration times to be those that convert to z scores between – 2 and 2, is a duration time of 110 sec usual or unusual? Why or why not?