• Question 3 (20 points)
For a given shop, We record the volume of sales for 30 days and we have the following data
day sales day sales day sale
1 900 11 870 21 890
2 850 12 890 22 1050
3 1000 13 920 23 1020
4 1200 14 760 24 1200
5 1000 15 1000 25 1010
6 960 16 1100 26 960
7 1010 17 1050 27 755
8 1105 18 450 28 880
9 450 19 760 29 920
10 760 20 800 30 900
(i) Compute the average volume of sales for these 30 days.
(ii) Consider the following three sample of 6 days
Sample 1: 1000,1050,960,450,880,920
Sample 2: 1105,1200,760,960,890,1000
Sample 3: 450,920,870,1200,1020,1105.
For each sample, compute the sampling error.
(iii) Select a sample of 5 observations using the systematic sampling method (explain your steps).