The mass of a high-precision turbine blade is modelled by a normal distribution with a mean of 450.0450.0450.0 g and a standard deviation of 12.412.412.4 g. After a change in the manufacturing process, a quality control engineer suspects that the mean mass of the blades has decreased. A random sample of 505050 blades is measured, and the sample mean mass is found to be 446.2446.2446.2 g. Carry out a hypothesis test at the 2%2\%2% significance level to investigate the engineer's suspicion.
162 exam-style questions on AQA A Level Maths 2.5 O: Statistical hypothesis testing, covering 2.5.1 Language of hypothesis testing, 2.5.2 Hypothesis test for a binomial proportion, and 2.5.3 Hypothesis test for a Normal mean (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.