The masses of a particular variety of apple are normally distributed with a mean of 180 g. It is found that 15% of the apples have a mass greater than 200 g.
Find the standard deviation of the masses of these apples.
390 exam-style questions on AQA A Level Maths 2.4 N: Statistical distributions, covering 2.4.1 Discrete distributions and the binomial, 2.4.2 The Normal distribution (A-level only), and 2.4.3 Selecting an appropriate distribution (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.