Chapter 1.2, Problem 68E

a.

To determine

To construct: The histogram using the provided data of travel time.

Explanation of Solution

Given:

The data set is:

17.6	23.6
17.7	17.7
24.2	25
24.6	20.7
29.1	26.8
20.9	23.9
30.9	24.1
23.4	23.6
15.5	25.9
22.1	27.3
20	25.5
21.8	20.1
25	27.9
22.3	22.3
22.9	18.2
15.9	18.5
23.5	22.4
24.6	25.1
20.8	22.3
21.2	30.6
26.9	26.6
25.2	23.4
25.6	22
20.8	24
17.9	22.9
29.2

Calculation:

To construct the histogram, frequency distribution is required and it could be constructed as:

  

Graph:

The histogram could be constructed as:

  

b.

To determine

To describe: The shape of the provided distribution. Also, find the common interval of travel times.

Explanation of Solution

From the above histogram, it can be concluded that the distribution of DRP scores is approximately normal that tells that the sample population data is also normally distributed.

It could be seen from the frequency distribution constructed in above part; the frequency is the highest for the interval 22-24. Thus, it could be said that 22-24 is the common interval of travel times.