The weight of organic apples in a grocery store follows a normal distribution with a mean of 150 g and a standard deviation of 12 g.
Find the probability that a randomly selected apple weighs more than 165 g.
Write down a null and alternative hypothesis for a two-tailed test.
A farmer takes a sample of 15 apples and finds a mean weight of 158 g. Test at the 5% significance level whether there is evidence that the mean weight of apples has changed.
390 exam-style questions on OCR A Level Maths 2.4 Statistical Distributions, covering 2.4.1 Discrete probability distributions, 2.4.2 Binomial distribution as a model, 2.4.3 Calculating binomial probabilities, 2.4.4 Mean and variance of the binomial (A-level only), 2.4.5 Normal distribution as a model (A-level only), 2.4.6 Probabilities using the normal distribution (A-level only), 2.4.7 Links to histograms, mean and standard deviation (A-level only), and 2.4.8 Selecting an appropriate distribution (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.