Another ride Another variable in the Chicago taxi data reports the total paid for the ride. A 90% confidence interval for the difference mweekend - mweekday is -$2.12 to -$0.87.

a) The endpoints of this confidence interval are negative numbers. What does that indicate?

b) What does the fact that the confidence interval does not contain 0 indicate?

c) If we use this confidence interval to test the null hypothesis that mweekend - mweekday = 0, what is the alpha level that corresponds to this interval?

d) The mean price of a weekend taxi ride is about $17.50.

Do you think the effect size in the difference between mean weekend and mean weekday rides is large enough to be important? Explain.