9709 P61 - Jun 2010 - Q4
2438
The numbers of rides taken by two students, Fei and Graeme, at a fairground are shown in the following table.
| Roller coaster | Water slide | Revolving drum | |
|---|---|---|---|
| Fei | 4 | 2 | 0 |
| Graeme | 1 | 3 | 6 |
(i) The mean cost of Fei’s rides is $2.50 and the standard deviation of the costs of Fei’s rides is $0. Explain how you can tell that the roller coaster and the water slide each cost $2.50 per ride. [2]
(ii) The mean cost of Graeme’s rides is $3.76. Find the standard deviation of the costs of Graeme’s rides. [5]
