Question

A traffic inspector has counted the number of vehicles passing through a certain point in 100 successive 20 – minute time periods. The observations are listed below.

23	20	16	18	30	22	26	15	5	18
14	17	11	37	21	6	10	20	22	25
19	19	19	20	12	23	24	17	18	18
27	16	28	26	15	29	19	35	20	17
12	30	21	22	20	15	18	16	23	24
15	24	28	19	24	22	17	19	8	18
17	18	23	21	25	19	20	22	21	23
16	20	19	11	23	17	23	13	17	26
26	14	15	16	27	18	21	24	33	20
21	27	18	22	17	20	14	21	22	10

You are required to:

a) Present these data on a grouped frequency distribution with class width of 5 for each class starting with 5 to 9, 10 to 14 and so on.                                    [5 marks]

b) Determine the real class limits and hence show the data on a histogram. [5marks]

c) Estimate the (I) mean (ii) Mode and (iii) Median.        [4 + 6+6 = 10 marks]

d) Estimate the (I) Quartiles (ii) Quartile Deviation (iii) Sample variance (iv) Sample standard deviation.           [6 + 2 + 4 + 2 = 14 marks]

e) Find the (I) Coefficient of variation (ii) Coefficient of Skewness.               [3 + 3 = 6 marks]

Answer 1