An agricultural scientist observed that the product moment correlation coefficient between the amount of rainfall (in mm) and the yield of a specific crop (in tonnes per hectare) for a sample of 30 farms was 0.412. The data is assumed to come from a bivariate normal distribution. Carry out a hypothesis test at the 5% significance level to determine whether there is a positive correlation between rainfall and crop yield. The critical value for the correlation coefficient at the 5% significance level for a sample size of 30 is 0.3061.
355 exam-style questions on OCR (MEI) A Level Maths 2.5 Statistical Hypothesis Testing, covering 2.5.1 Process and language of hypothesis testing, 2.5.2 When to apply 1-tail and 2-tail tests, 2.5.3 Significance level and incorrect rejection, 2.5.4 Null and alternative hypotheses (binomial), 2.5.5 Conduct a binomial hypothesis test, 2.5.6 Critical and acceptance regions (binomial), 2.5.7 Distribution of the sample mean (A-level only), 2.5.8 Hypothesis test for a single mean (A-level only), 2.5.9 Critical and acceptance regions (mean) (A-level only), 2.5.10 Correlation as closeness to a straight line (A-level only), 2.5.11 Inference using a correlation coefficient (A-level only), and 2.5 Statistical Hypothesis Testing. Each one has a worked solution and a mark scheme showing where the marks go.