A botanist observes that the number of seeds, SSS, that germinate in a large nursery plot follows a binomial distribution S∼B(n,p)S \sim \text{B}(n, p)S∼B(n,p). The expected number of germinated seeds is 200.
State the variance of SSS in terms of ppp.
A normal distribution is used as an approximation for SSS. Using this approximation and a continuity correction, the probability that 180 or fewer seeds germinate is approximately 0.0384.
Show that 200−200p=11.02\sqrt{200 - 200p} = 11.02200−200p=11.02 to 4 significant figures.
Hence find the value of ppp, giving your answer to 2 significant figures.
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.