The weights of bags of sugar, W W\,W grams, are normally distributed. It is known that P(W<490)=0.15P(W < 490) = 0.15P(W<490)=0.15 and P(W>515)=0.25P(W > 515) = 0.25P(W>515)=0.25.
Find the mean and standard deviation of the weights of the bags of sugar.
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.