The lifetime of a certain type of battery is normally distributed with a mean of 60 hours. Given that 8% of the batteries last less than 48 hours, find the standard deviation of the lifetimes.
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.