Theory question 106
StatisticsThe table shows the distribution of distance (in km) of 60 villages from a state capital.
Distance (in km): 0−19, 20−29, 30−39, 40−49, 50−69, 70−99, 100−149
Number of villages: 12, 7, 6, 8, 5, 9, 10
Draw a histogram for the distribution.
Show the model answer
Model answer
Class boundaries and widths: −0.5–19.5 (20), 19.5–29.5 (10), 29.5–39.5 (10), 39.5–49.5 (10), 49.5–69.5 (20), 69.5–99.5 (30), 99.5–149.5 (50).
Widths differ, so plot frequency density (frequency ÷ width): 0.6, 0.7, 0.6, 0.8, 0.25, 0.3, 0.2 (or per 10 km: 6, 7, 6, 8, 2.5, 3, 2).
Draw touching bars on the class boundaries with these heights; label both axes and state the scale.
Explanation
With unequal class widths the bar areas, not heights, must match the frequencies.