A published study found that 75% of diesel cars in a large random sample registered in 2022 had CO emissions of less than 0.3 g/km.
Jo wants to investigate whether the proportion of diesel cars with CO emissions of less than 0.3 g/km has changed in the later year. She will carry out a hypothesis test at the 10% significance level, with a probability of at most 0.05 in each tail, using a random sample of 30 diesel cars registered in the later year.
State suitable null and alternative hypotheses for Jo's test.
Using a 10% significance level, find the critical region for Jo's test.
In her random sample, Jo finds 22 cars with CO emissions of less than 0.3 g/km. State Jo's conclusion in context.
40 exam-style questions on WJEC A Level Maths 2.5 Statistical hypothesis testing, covering 2.5.1 Statistical hypothesis testing, 2.5.2 Statistical hypothesis testing, 2.5.3 Statistical hypothesis testing, 2.5.4 Statistical hypothesis testing, and 2.5 Statistical hypothesis testing. Each one has a worked solution and a mark scheme showing where the marks go.