A retail manager in a discount store wants to establish a policy of the number of cashiers to have on hand and also when to open a new cash register. The first step in this process is to determine the rate at which customers arrive at the cash register. One day, the man- ager observes the following times (in minutes) between arrivals of customers at the cash registers:
|
0.1
|
2.6
|
2.9
|
0.5
|
|
1.2
|
1.8
|
4.8
|
3.3
|
|
1.7
|
0.2
|
1.5
|
2.0
|
|
4.2
|
0.6
|
1.0
|
2.6
|
|
0.9
|
3.4
|
1.7
|
0.4
|
a Plot a CDF based on these data.
b What kind of theoretical distribution do you think would be appropriate for these data? Why?
c Calculate the sample mean and sample standard deviation of the data, and use these to estimate parameters for the theoretical distribution chosen in part b.
d Plot a few points from the CDF of your theoretical distribution, and draw a smooth curve through them. How does this theoretical curve compare to the data-based CDF?