The daily commute time for employees at a tech firm is normally distributed with a mean of 45 minutes and a standard deviation of 6 minutes.
Find the probability of a commute taking longer than 58 minutes.
Write down a null and alternative hypothesis for a two-tailed test.
A survey of 12 randomly selected employees finds a mean commute time of 49.5 minutes. Test at the 10% significance level whether there is evidence that the mean commute time 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.