The mass of flour in a bag, W W\,W grams, is normally distributed. It is known that 5% of the bags weigh less than 495 g and 12% of the bags weigh more than 510 g.
Calculate the mean, μ\muμ, and the standard deviation, σ\sigmaσ, of the masses of these bags.
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.