Foundation November 2019 Paper 3 Q7
7 Jenny has a five-sided biased spinner.
The sectors are coloured red, blue, green, yellow and white.
She spins the spinner 100 times.
The table shows the number of times the spinner lands on each colour.
| Colour | Frequency |
|---|---|
| Red | 28 |
| Blue | 38 |
| Green | 6 |
| Yellow | 0 |
| White | 28 |
| Total | 100 |
Jenny uses her data to estimate the probability of the spinner landing on each colour.
(a) Write down Jenny’s estimate for the probability of landing on red. [1]
(b) Jenny then writes in some of the colours on this probability scale.
(i) Write the correct colour in the box. [1]
(ii) Explain why Jenny’s estimate for the probability of landing on yellow cannot be the actual probability. [1]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| \(\dfrac{28}{100}\) oe or 0.28 or 28% | 1 | Do not accept ratio or in words Ignore attempts to change to decimals or cancel once correct answer seen | |
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| (i) Blue | 1 | ||
| (ii) Yellow is [a sector] on the spinner oe or Yellow is a possible outcome oe | 1 | Anything saying the spinner can land on yellow or yellow is on the spinner. Contradictory statements score 0. | |
Exemplar responses
Exemplar responses for Q7bii
| Example | Mark | Reason |
|---|---|---|
| It can’t be the actual probability because there is a yellow ball in the bag | 1 | BOD the reference to balls, reward recognition yellow exists |
| If you did it again you (could) land on yellow | 1 | Recognises yellow is an outcome |
| She could get yellow as it in the spinner | 1 | Recognises yellow is on the spinner |
| Her spinner is biased so would land on yellow if it was spun over 100 times | 1 | Recognises yellow is on spinner |
| The spinner is biased. The probability of yellow is not the actual one. | 0 | Does not say yellow is on the spinner |
| The total would not add up to 100. Yellow would have to be 12 | 0 | Does not say yellow is on the spinner |
| Because she has no yellows | 0 | Does not say yellow is on the spinner |
| Because she has a biased 5 sided spinner | 0 | Does not say yellow is on the spinner |