Marine biologists monitoring a coral reef find that the probability of a specific coral colony showing signs of thermal stress is 0.40. They survey a reef section containing 200 individual colonies.
Using a suitable approximation, estimate the probability that more than 75 colonies in the section show signs of thermal stress.
A researcher examines 3 separate sections of the reef, each containing 200 colonies.
Estimate the probability that at least 76 colonies show signs of thermal stress in each of the 3 sections.
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.