The accompanying data file shows the net profit (Net_Profit)  counter sales (Counter_Sales), and drive-through sales (Drive_Sales) for a chain of 100 fast-food restaurants. All variables are measured in millions of dollars.

a. Calculate the sample standard deviation for counter sales and drive-through sales. According to this measure of dispersion, which variable exhibited higher variability?

b. Calculate the mean absolute deviation (MAD) for counter sales and drive-through sales. According to this measure of dispersion, which variable exhibited higher variability?

Net_Profit	Counter_Sales	Drive_Sales
1.5	8.4	7.7
0.8	3.3	4.5
1.2	5.8	8.4
1.4	10.0	7.8
0.2	4.7	2.4
0.8	7.7	4.8
0.6	4.5	2.5
1.3	8.6	3.4
0.4	5.9	2.0
0.6	6.3	4.1
1.5	8.4	7.7
0.8	3.3	4.5
1.2	5.8	8.4
1.4	10.0	7.8
0.2	4.7	2.4
0.8	7.7	4.8
0.6	4.5	2.5
1.3	8.6	3.4
0.4	5.9	2.0
0.6	6.3	4.1
1.5	8.4	7.7
0.8	3.3	4.5
1.2	5.8	8.4
1.4	10.0	7.8
0.2	4.7	2.4
0.8	7.7	4.8
0.6	4.5	2.5
1.3	8.6	3.4
0.4	5.9	2.0
0.6	6.3	4.1
1.5	8.4	7.7
0.8	3.3	4.5
1.2	5.8	8.4
1.4	10.0	7.8
0.2	4.7	2.4
0.8	7.7	4.8
0.6	4.5	2.5
1.3	8.6	3.4
0.4	5.9	2.0