You would like to know if operating red-light camera can actually reduce the number of traffic violation. We know that the average number of tickets before the implementation of red-light camera on daily basis was 15. After a careful experiment, you find that the average number went down to 11 with a standard deviation of 3. Z statistics turns out to be 2.14. Interpret the finding here. Describe null hypothesis (Ho) and alternative hypothesis (Ha), the finding, and whether or not to reject Ho.