=+29. Bank tellers. A bank is studying the average time that it takes 6 of its tellers to serve a customer. Customers line up in the queue and are served by the next available teller.

Here is a boxplot of the times it took to serve the last 140 customers.

60 30 90 120 123 4 5 6 Time (min)

Teller Source DF Sum of Squares Mean Square F-ratio P-value Teller 5 3315.32 663.064 1.508 0.1914 Error 134 58919.1 439.695 Total 139 62234.4