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.
209 exam-style questions on CCEA A Level Maths 4.6 Statistical hypothesis testing (A-level only), covering 4.6.1 Statistical hypothesis testing (A-level only), 4.6.2 Statistical hypothesis testing (A-level only), 4.6.3 Statistical hypothesis testing (A-level only), 4.6.4 Statistical hypothesis testing (A-level only), and 4.6.5 Statistical hypothesis testing (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.