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 CIE IGCSE Maths Probability Equation Questions with exam-style questions for Core and Extended tier. 7 questions, matched to the CIE IGCSE Maths (0580) specification and written in Paper 1 and Paper 3 (Core) or Paper 2 and Paper 4 (Extended) 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.
