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.
616 exam-style questions on Edexcel A Level Maths The Normal Distribution, covering 3.1 The Normal Distribution, 3.2 Finding Probabilities for Normal Distributions, 3.3 The Inverse Normal Distribution Function, 3.4 The Standard Normal Distribution, 3.5 Finding the mean and standard deviation, 3.6 Approximating a Binomial Distribution, and 3.7 Hypothesis Testing with the Normal Distribution. Each one has a worked solution and a mark scheme showing where the marks go.