Nadia is investigating whether there is a correlation between the age of a second-hand car, in years, and its market value, in pounds.
Suggest a suitable null hypothesis and a suitable alternative hypothesis for a two-tailed test.
Nadia takes a random sample of 18 second-hand cars and obtains a product moment correlation coefficient of -0.45.
For n=18n = 18n=18, the critical value for a two-tailed test at the 5% level for the population correlation coefficient is 0.4683.
Carry out the hypothesis test at the 5% significance level.
121 exam-style questions on OCR A Level Maths 2.2 Data Presentation and Interpretation, covering 2.2.1 Tables and diagrams for single variable data, 2.2.2 Area in a histogram, 2.2.3 Scatter diagrams and regression lines, 2.2.4 Informal interpretation of correlation, 2.2.5 Correlation and causation, 2.2.6 Measures of average and spread, 2.2.7 Calculations of mean and standard deviation, 2.2.8 Outliers, 2.2.9 Selecting or critiquing data presentation, and 2.2.10 Cleaning data. Each one has a worked solution and a mark scheme showing where the marks go.