Foundation June 2019 Paper 3 Q19
19
(a) This spinner has two grey sections, two white sections and one black section.
Vlad says
The probability of the spinner landing on black is \(\dfrac{1}{5}\).
Explain why Vlad is not correct. [1]
(b) The graph shows the cost of a litre of petrol for the last six months of 2017.
Explain why this graph is misleading. [1]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| Correct answer based on angle or area/arc length | 1 | The angle [for black]
| Accept 26 to 30 for “the angle” Accept “not equal to” for “too small” or “less than” See appendix |
Appendix
Question 19a
| Response | Mark | |
|---|---|---|
| A | The black section does not cover 1/5 of the spinner | 1 “covering” implies area |
| B | The angle is \(28^\circ\). It should be \(72^\circ\). | 1 |
| C | 1/5 is \(72^\circ\) and the black section is less than this | 1 |
| D | The angle is only 28. | 1 Implied comparison with correct angle BOD Minimum case |
| E | Because 30/360 is 1/12 | 1 comparing angle as fraction with common numerator with 1/5 (which is given) (3/36 is not enough to compare) |
| F | Because 28/360 = 0.07[…] not 0.2 | 1 Correct comparison (but (26 to 30)/360 needed for evidence of working with angle) |
| G | The angle is \(28^\circ\). | 0 Does not say that it should be 72 or is too small |
| H | The sections are not of equal area | 0 |
| I | The sections are not of equal width | 0 |
| J | The black section is the smallest section | 0 |
| K | The spinner is unequal and some spaces are the same colour but different size | 0 |
| L | It’s more like a tenth | 0 No angle used to justify |
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| Any comment recognising limitations in range of the vertical scale | 1 | EG It does not start at zero or It starts at 113 See appendix | |
Appendix
Question 19b
| Response | Mark | |
|---|---|---|
| A | The graph starts at 113 | 1 Recognises limitation in scale |
| B | The y-axis is only from 113 to 121 | 1 Recognises limitation in scale |
| C | Because you don’t see anything below 113 | 1 Recognises limitation in scale |
| D | You can’t read between the numbers on the scale | 0 Does not recognise limitations in the range of the scale |
| E | It doesn’t start from the bottom of the graph and the units go up in an unusual pattern. | 0 Too vague. |
| F | It looks as though there has been a drastic increase in price when there hasn’t. | 0 Not explained why the scale causes this |
| G | There are lines joining the points. | 0 Irrelevant |
| H | Because the cost varies throughout the month. | 0 True but describing patterns |
| I | Because it would have fluctuated. | 0 True but describing patterns |
| J | You don’t see the bottom of the graph | 0 Too vague |