There are some red counters and some blue counters in a bag.
The ratio of red counters to blue counters is 3:1.
Two counters are removed at random.
The probability that both the counters taken are blue is 120\displaystyle \frac{1}{20}201
Work how many counters were in the bag before any counters were removed.
Practise Oxford AQA IGCSE Maths Probability Equation Questions with exam-style questions for Core and Extended tier. 7 questions, matched to the Oxford AQA IGCSE Maths (9260) specification and written in Paper 1 and Paper 2 (Core: 1C and 2C; Extension: 1E and 2E) style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.