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.
390 exam-style questions on OCR (MEI) A Level Maths 2.4 Probability Distributions, covering 2.4.1 Recognise binomial situations, 2.4.2 Probability of success p, 2.4.3 Calculate binomial probabilities, 2.4.4 Mean of the binomial distribution, 2.4.5 Expected frequencies for binomial, 2.4.6 Probability functions and discrete random variables, 2.4.7 Numerical probabilities for a simple distribution, 2.4.8 Normal distribution as a model (A-level only), 2.4.9 Shape of the Normal curve (A-level only), 2.4.10 Linear transformation and standardising (A-level only), 2.4.11 Symmetry and inflection of Normal curve (A-level only), 2.4.12 Calculate probabilities from a Normal distribution (A-level only), 2.4.13 Model with probability distributions, and 2.4 Probability Distributions. Each one has a worked solution and a mark scheme showing where the marks go.