In: Math
In a debate on altering the traffic system in the city centre, measurement of a number of cars per minutes were taken at two intersections during the hours between 07h00 and 08h00 (when the roads were most busy). The results are shown in the table below:
Number of cars |
frequency |
10-14 |
5 |
15-19 |
8 |
20-24 |
10 |
25-29 |
12 |
30-34 |
14 |
35-39 |
5 |
40-44 |
3 |
45-48 |
3 |
Descriptive Statistics
First we construct the following table:
Class limits | Class boundaries | x | f | xf | x2f | cumulative freq |
10-14 | 9.5-14.5 | 12 | 5 | 60 | 720 | 5 |
15-19 | 14.5-19.5 | 17 | 8 | 136 | 2312 | 13 |
20-24 | 19.5-24.5 | 22 | 10 | 220 | 4840 | 23 |
25-29 | 24.5-29.5 | 27 | 12 | 324 | 8748 | 35 |
30-34 | 29.5-34.5 | 32 | 14 | 448 | 14336 | 49 |
35-39 | 34.5-39.5 | 37 | 5 | 185 | 6845 | 54 |
40-44 | 39.5-44.5 | 42 | 3 | 126 | 5292 | 57 |
45-48 | 44.5-49.5 | 47 | 3 | 141 | 6627 | 60 |
Total | 60 | 1640 | 49720 |