The masses of metal components, M M\,M grams, are normally distributed with a standard deviation of 3.2. Given that P(M<12)=0.42P(M < 12) = 0.42P(M<12)=0.42, calculate the mean mass of the components.
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.