A materials scientist is evaluating the tensile strength of two newly developed carbon-fiber composites: 'Aeroflex' and 'Durawave'. The scientist believes that Aeroflex has a mean tensile strength that is more than 50 MPa greater than that of Durawave.
A random sample of 200 specimens of Aeroflex found a mean tensile strength of 3452 MPa with a standard deviation of 78 MPa.
A random sample of 250 specimens of Durawave found a mean tensile strength of 3384 MPa with a standard deviation of 72 MPa.
Stating your hypotheses clearly, test the scientist's claim at the 5% level of significance.
State whether it was necessary to assume that the tensile strengths of the specimens are normally distributed. Give a reason for your answer.
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.