Compute Using: The data to the left, Microsoft Excel functions, or Data Analysis Toolpak, Regression

A critically important aspect of customer service in a supermarket is the waiting time at the checkout

(defined as the time the customer enters the line until he or she is served). Data were collected during time

periods in which a constant number of checkout counters were open. The total number of customers in the

store and the waiting time (in minutes) were recorded.

1. Construct a scatter plot comparing # of Customers to Wait Time.

2. Determine the regression coefficient, b0 and b1 (be sure to indicate the units for b0 and b1!!). State the regression equation.

3. Interpret the meaning of the slope, b1.

4. Predict the waiting time when there are 20 customers in the store.

5. Determine the coefficient of determination, r2, and interpret its meaning.

6. How useful do you think this regression model is for predicting wait time at the checkout line?

7. Suppose you just implemented an improvement project where you attempted to improve wait time

at the checkout in a supermarket and these are your findings. What would you conclude about

your study?

Supermarket Data
Day	Customers	Time
1	15.00	1.50
2	18.00	1.20
3	9.00	0.80
4	7.00	0.50
5	19.00	2.00
6	30.00	2.50
7	27.00	3.00
8	13.00	2.00
9	11.00	1.70
10	9.00	0.50
11	21.00	2.00
12	35.00	5.20
13	25.00	2.30
14	8.00	0.20
15	16.00	0.70
16	21.00	2.50
17	17.00	1.00
18	22.00	3.80
19	16.00	1.50
20	24.00	2.80
21	14.00	1.00
22	15.00	1.70
23	21.00	3.00
24	27.00	2.80
25	17.00	1.00
26	21.00	2.50
27	20.00	2.90
28	31.00	3.40
29	38.00	4.00
30	42.00	4.80