Foundation June 2018 Paper 1 Q7
7 Here is a probability scale.
It shows the probability of each of the events A, B, C and D.
(a) Write down the letter of the event that is certain. (1)
(b) Write down the letter of the event that is unlikely. (1)
There are 12 counters in a bag.
3 of the counters are red.
1 of the counters is blue.
2 of the counters are yellow.
The rest of the counters are green.
Caitlin takes at random a counter from the bag.
(c) Show that the probability that this counter is yellow or green is \(\dfrac{2}{3}\) (3)
| Answer | Mark | Mark scheme |
|---|---|---|
| D | B1 | cao |
| Answer | Mark | Mark scheme |
|---|---|---|
| B | B1 | cao |
| Answer | Mark | Mark scheme |
|---|---|---|
| Shown | M1 | for number of green counters, eg \(12 - (3 + 1 + 2) = 6\) OR for \(\dfrac{3}{12}\) oe or \(\dfrac{1}{12}\) oe or \(\dfrac{2}{12}\) oe linked to the appropriate colour |
| M1 | for \(1 - \left(\text{``}\dfrac{3}{12}\text{''} + \text{``}\dfrac{1}{12}\text{''}\right) \left(= \dfrac{8}{12}\right)\) or \(\text{``}\dfrac{2}{12}\text{''} + \dfrac{\text{``}6\text{''}}{12} \left(= \dfrac{8}{12}\right)\) OR for method to find \(\dfrac{2}{3}\) of 12, eg. \(12 \div 3 \times 2\ (= 8)\) | |
| C1 | for correct conclusion supported by accurate figures, eg \(\dfrac{8}{12} = \dfrac{2}{3}\) or \(\dfrac{2}{3}\) of \(12 = 8\) and number of yellow + green \(= 2 + 6 = 8\) |
Additional guidance
This is awarded for a correct first step
This is awarded for a fully correct method from which the correct answer of \(\dfrac{2}{3}\) can be found
Sight of \(\dfrac{8}{12}\) gets M2