There are n n\,n counters in a bag.
8 of the counters are red and the rest are blue.
Adam takes a counter from the bag at random and does not replace it. He then takes another counter at random from the bag.
The probability that Adam takes two blue counters is 15\displaystyle \frac{1}{5}51
Show that n2−21n+90=0n^2 - 21n + 90 = 0n2−21n+90=0
Find the value of nnn.
Practise Edexcel IGCSE Maths Probability Equation Questions with exam-style questions for IGCSE Maths. 7 questions, matched to the Edexcel IGCSE Maths (4MA1) specification and written in Paper 1 and Paper 2 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.