Higher November 2020 Unit 2 Q18
18. A large number of people took part in a survey that was carried out to find the popularity of three different walks in West Wales.
Each person surveyed was asked, independently, to select their one favourite walk.
The table below shows the results of the survey.
| Walk | The percentage of people who selected the walk |
|---|---|
| The Preseli Ridge | 70% |
| Ramsey Sound | 20% |
| Laugharne | 10% |
Three girls, Constance, Scarlett and Clementine, were chosen at random from all of the people surveyed.
They were asked which walk they had selected.
Calculate the probability that the three girls had each selected a different walk. [3]
| Scheme | Marks | Comments |
|---|---|---|
| 0·7×0·2×0·1×6 | M2 | M1 for sight of 0·7×0·2×0·1 OR 0·014 OR 7/500 or equivalent. |
| = 0·084 or equivalent | A1 | Fractional answer: 21/250 or equivalent. (ISW) |