The mass of a bag of flour produced at a factory is normally distributed with a mean of 1500 g and a standard deviation of 20 g.
Find the probability of a bag weighing more than 1545 g.
The quality control manager suspects that the mean mass of the flour bags has changed.
Write down a null and alternative hypothesis for a two-tailed test.
They take a random sample of 25 bags and find a mean mass of 1512 g.
Test at the 5% significance level whether there is evidence that the mean mass has changed.
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.