Healthy-Greens Farm grows organic cucumbers. They are considering a new irrigation system and hope it will increase the average yield per plant by at least 1.5 kg. The variance of the yield using the existing system is 0.6 kg2, and the variance of the yield using the new system is 0.8 kg2. A random sample of 50 plants using the existing system has a mean yield of 6.2 kg. A random sample of 80 plants using the new system has a mean yield of 8.1 kg.
Stating your hypotheses clearly, test at the 5% level of significance whether or not there is evidence that the mean yield with the new system is more than 1.5 kg greater than the mean yield with the existing system.
Explain the relevance of the Central Limit Theorem to the test conducted in part (a).
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.