After receiving numerous complaints about the speed on a section of road, the county government collected random samples of 5 cars for 6 consecutive days. They recorded the speed of every car in the daily sample. The results are presented in the Table 1 below. This serves as the foundation for analyzing the process and developing your control charts.

Table 1: Original Samples Day Speed of cars (kph) 1 70, 60, 61, 69, 64 2 64, 71, 60, 69, 60 3 61, 64, 72, 65, 63 4 69, 68, 65, 62, 60 5 58, 68, 65, 68, 62 6 60, 59, 70, 67, 62

Residents suggest that a radar system that displays to drivers how fast they are going will slow them down and reduce the average speed and the number of cars speeding. The county installs the system and collects samples of 5 cars for 5 consecutive days. This data is provided in Table 2. This is the data from the adjusted process with the monitor.

Table 2: After Speed Display Added Samples Day Speed of cars (kph) 1 57, 59, 73, 70, 65 2 58, 59, 75, 68, 64 3 57, 60, 61, 71, 73 4 54, 61, 67, 69, 77 5 65, 57, 74, 73, 64

They now want to determine whether there has been any change in the process as a result of the speed indicator. Construct the appropriate 3 sigma process control analysis with the original data and determine whether you conclude that there has been any change due to the installation of the speed monitoring and display system (i.e. that the speed display is an assignable cause that has changed the process) by evaluating the post change data in the original control charts. What is your conclusion?