There are 6 blue pens and k k\,k black pens in a box.
Liam takes a pen from the box at random.
He puts the pen back into the box.
Liam then takes another pen at random from the box.
The probability that both pens Liam takes are blue is 964\displaystyle \frac{9}{64}649
Work out how many black pens are in the box.
Practise Edexcel GCSE Maths Probability Equation Questions with exam-style questions for Foundation and Higher tier. 28 questions, matched to the Edexcel GCSE Maths (1MA1) specification and written in Paper 1, Paper 2 and Paper 3 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.