II. Evaluating a Speed Camera A local council is considering putting in a new speed camera and
wants to know if it would be effective. To see what might happen,
they put up a dummy camera and measured the speeds of four
groups of 15 cars.
The data is given below; all speeds are in miles per hour and the
speed limit was 30mph.
11am - No Camera
30 30 18 30 31 28 29 32
30 28 31 28 30 36 28
llam - Dummy Camera
23 30 27 20 30 29 28 29
31 35 2431 29 31 27
5pm - No Camera
3730 35 43 38 34 32 30
41 2935 34 30 40 38
5pm – Dummy Camera
28 30 31 29 29 32 30 30
32312731 32 30 33
Using the same axis, draw four parallel box-and-whisker plots to represent this information.
Write a paragraph to explain to the council what the box-and-whisker plots show, and make a
recommendation about buying a permanent camera. A good response would:
Consider whether the dummy camera had different effects at different times of
day
Use specific mathematical words including 'median', 'maximum' and
'interquartile range'