Scores on a professional certification exam are modeled by a normal distribution.
15% of candidates score lower than 60 marks. 10% of candidates score higher than 85 marks.
Calculate the mean and standard deviation of the scores.
149 exam-style questions on OCR (MEI) A Level Maths 2.4.12 Calculate probabilities from a Normal distribution (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.