The height of sunflower seedlings in a nursery is normally distributed with a mean of 15.5 cm and a standard deviation of 1.2 cm.
Find the probability that a randomly selected seedling has a height of less than 13.0 cm.
Write down the null and alternative hypotheses to test if the mean seedling height is lower than 15.5 cm.
A sample of 25 seedlings is measured and the mean height is found to be 15.0 cm. Carry out a test at the 2.5% significance level to see if there is evidence that the mean height of the seedlings is less than 15.5 cm.
316 exam-style questions on OCR A Level Maths 2.5 Statistical Hypothesis Testing, covering 2.5.1 The language of hypothesis testing, 2.5.2 Hypothesis test for a binomial proportion, 2.5.3 Inference and significance level, 2.5.4 Sample mean as a random variable (A-level only), 2.5.5 Hypothesis test for the mean of a normal distribution (A-level only), 2.5.6 Pearson's product-moment correlation coefficient, and 2.5.7 Hypothesis test using Pearson's coefficient (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.