For a random sample of 30 cars, the correlation coefficient between a car's CO emission and its CO2 _2\,2 emission is 0.58.
For n=30n = 30n=30, the critical value for a one-tailed test at the 5% level for the population correlation coefficient is 0.3061.
State what a correlation coefficient of 0.58 tells you about the points on a scatter diagram of these data.
Compare 0.58 with the critical value and state what this suggests about the population.
Explain why this result does not show that a car's CO2 _2\,2 emission causes its CO emission.
157 exam-style questions on AQA A Level Maths 2.2.2 Scatter diagrams and correlation. Each one has a worked solution and a mark scheme showing where the marks go.