Question 7.107

7.107 Average number of cars in the drive-thru lane.

Refer to the previous exercise. A related benchmark measure was the number of cars observed in the drive-thru lane. A summary for the same two chains is shown here.

Chain
Taco Bell 308 2.11 2.83
McDonald’s 317 3.81 4.56
  1. Is there a difference in the average number of cars in the drive-thru lane? Test the null hypothesis that the chains’ average number of cars is the same. Use a significance level of 0.05.
  2. These data can only take the values 0, 1, 2, . . . , so they are definitely not Normal. The standard deviations are also much larger than the means, suggesting strong skewness. Does this imply the analysis in part (a) is not reasonable? Explain your answer.

7.107

(a) . The data are significant at the 5% level, and there is evidence the average number of cars in the drive-thru lane between the two chains is different. (b) Because , the procedures can be used for skewed data, as long as there are no outliers.