23. Movie lengths IT.' Exercise 21 looked at the running times of movies released in 2005. The standard deviation
of these running times is 19.6 minutes, and the quartiles
are Qi 97 minutes and Q; = 119 minutes.
a) Write a sentence or two describing the spread in
running times based on
i) the quartiles.
ii) the standard deviation.
b) Do you have any concerns about using either of these
descriptions of spread? Explain.

(b) suppose that consolidated power decides to use a level of significance of α = .05, and suppose a random sample of 100 temperature readings is obtained. if the sample mean of the 100 temperature readings is x⎯⎯ = 60.990, test h0 versus ha and determine whether the power plant should be shut down and the cooling system repaired. perform the hypothesis test by using a critical value and a p-value. assume σ = 5. (round your z to 2 decimal places and p-value to 4 decimal places.)