A random sample of size nnn is taken from a population that is normally distributed with mean 252525 and standard deviation 444. Find the minimum sample size such that the probability of the sample mean being greater than 27.527.527.5 is less than 1%1\%1%.
225 exam-style questions on CCEA A Level Maths 4.5.1 Statistical distributions (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.