In a bag there are only red counters, blue counters, green counters and yellow counters.
A counter is taken at random from the bag.
The table shows the probabilities that the counter will be green or will be yellow.
| Colour | Red | Blue | Green | Yellow |
|---|---|---|---|---|
| Probability | 0.35 | 0.20 |
The probability that the counter will be red is twice the probability that the counter will be blue.
There are k k\,k green counters in the bag.
Work out, in terms of kkk, the number of red counters in the bag.
324 exam-style questions on CCEA GCSE Maths Probability. Each one has a worked solution and a mark scheme showing where the marks go.