There are 8 counters in a bag. Some of the counters are red. The remaining counters are blue. Two counters are taken at random from the bag. The probability that one counter of each colour are taken is 1528\displaystyle \frac{15}{28}2815.
Work out the possible numbers of red counters and blue counters.
You must show your working.
72 exam-style questions on Edexcel GCSE Maths Conditional Probability. Each one has a worked solution and a mark scheme showing where the marks go.