From Example 7, trading volumes for General Electric stock on Mondays and Fridays during
February through April of 2011 were given as follows

The Monday data have x = 51.82, s = 17.19, Q1 = 43, Median = 45, Q3 = 64.
The Friday data have x = 50, s = 11.34, Q1 = 41.5, Median = 47, Q3 = 54.5.
a. Construct a histogram or box plot of the Friday data. What assumptions are needed to construct a 95% confidence interval for μ? Point out any assumptions that seem questionable.
b. Using the Friday data and appropriate given summary statistics, show that the 95% confidence interval is (42.795, 57.205). Interpret it in context.
c. Check whether this data set has any potential outliers according to the criterion of (i) 1.5 * IQR below Q1 or above Q3 and (ii) 3 standard deviations from the mean.
d. The value 80 is quite a bit larger than the others. Delete this observation, find the new mean and standard deviation, and use software to construct the 95% confidence interval for μ. How does it compare to the 95% confidence interval (42.796, 57.204) using all the data?

Transcribed Image Text:

Mondays: Fridays: 45, 43, 43,66,91, 53, 35, 45, 29, 64, 56 43, 41,45,46, 61, 56, 80, 40.48, 49, 50, 41