The manager of a convenience store tracked total sales during a small sample of eight recent daytime shifts (an eight-hour period of the day). The total sales during these periods were as follows:

+2,243 +2,014 +1,964 +1,889 +2,502 +2,685

+2,146 +4,592.

(a) Does this sample appear to be normally dis- tributed on the basis of a normal quantile plot? Explain.

(b) On the basis of the CLT condition, do these data seem appropriate as the basis for a t-interval for the mean? Why or why not?

(c) Assuming that the data are a sample from a normally distributed population, find the 95% one-sample t-interval for the mean, both with and without the outlier. How does the 95% interval change if the last data point (the largest) is excluded?

(d) Explain why the lower endpoint of the 95% confidence t-interval is larger without the outlier than with the outlier.