Calgary in January The average January temperature in Calgary varies from year to year. These average January temperatures themselves have an average, over many past years, of –7.9 degrees Celsius, with a standard deviation of 5.0 degrees. Assume a Normal model applies.

a) During what percentage of years does Calgary have a January average above 0 degrees?

b) In the 20% coldest Januaries, the average January temperature reaches no higher than how many degrees?

c) Suppose you will be in Calgary for the next four years. Describe the sampling distribution model for the average of the next four January average temperatures. Assume climatic conditions are not changing.

d) What is the probability that the average of the next four January average temperatures will exceed –4 degrees? If this happens, would you consider this evidence of climatic warming (at least locally, in Calgary), or just Normal variation?