A motoring journalist believes that, for new petrol cars, there is a positive correlation between the engine size of a car and its carbon dioxide emissions.
She collects data from a random sample of 50 new petrol cars. The product moment correlation coefficient between engine size and carbon dioxide emissions for this sample is 0.31.
For n=50n = 50n=50, the critical value for a one-tailed test at the 2.5% level for the population correlation coefficient is 0.2787.
Carry out a hypothesis test at the 2.5% significance level to determine whether this sample provides evidence to support the journalist's belief.
244 exam-style questions on AQA A Level Maths 2.2 L: Data presentation and interpretation, covering 2.2.1 Single-variable data diagrams, 2.2.2 Scatter diagrams and correlation, 2.2.3 Central tendency, variation and standard deviation, 2.2.4 Outliers and cleaning data, and 2.2 L: Data presentation and interpretation. Each one has a worked solution and a mark scheme showing where the marks go.