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.
616 exam-style questions on Edexcel A Level Maths The Normal Distribution, covering 3.1 The Normal Distribution, 3.2 Finding Probabilities for Normal Distributions, 3.3 The Inverse Normal Distribution Function, 3.4 The Standard Normal Distribution, 3.5 Finding the mean and standard deviation, 3.6 Approximating a Binomial Distribution, and 3.7 Hypothesis Testing with the Normal Distribution. Each one has a worked solution and a mark scheme showing where the marks go.