Higher November 2017 Paper 3 Q10
10 There are only blue counters, yellow counters, green counters and red counters in a bag.
A counter is taken at random from the bag.
The table shows the probabilities of getting a blue counter or a yellow counter or a green counter.
| Colour | blue | yellow | green | red |
|---|---|---|---|---|
| Probability | 0.2 | 0.35 | 0.4 |
(a) Work out the probability of getting a red counter. (1)
(b) What is the least possible number of counters in the bag?
You must give a reason for your answer. (2)
You must give a reason for your answer. (2)
| Answer | Mark | Notes |
|---|---|---|
| 0.05 | B1 | for 0.05 oe |
| Answer | Mark | Notes |
|---|---|---|
| 20 | C1 | for stating that at least 20 required |
| Reason | C1 | for reason eg explains that number of each colour must be a whole number or that there must be (at least) 1 red counter or shows that \(0.05 = \dfrac{1}{20}\) |