A random sample of size n n\,n is taken from a population that is normally distributed with mean 25 and standard deviation 4.
Find the minimum value of n n\,n for which P(X‾>27.5)<0.01P(\overline X>27.5)<0.01P(X>27.5)<0.01.
328 exam-style questions on WJEC A Level Maths 4.2 Statistical distributions (A-level only), covering 4.2.1 Statistical distributions (A-level only), 4.2.2 Statistical distributions (A-level only), and 4.2.3 Statistical distributions (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.