The time, T T\,T minutes, taken for a student to complete a logic puzzle follows a normal distribution. Data shows that 25% of students complete the puzzle in less than 25 minutes, while 15% take more than 45 minutes.
Find the mean and standard deviation of the time taken to complete the puzzle.
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.