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2.4 Probability Distributions

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Question 89

An entomologist studies a population of beetles where the probability of an individual possessing iridescent wing cases is 0.2. A random sample of 20 beetles is collected.

a.

Find the probability that in this sample there will be:

(i) exactly 3 beetles with iridescent wing cases,

(ii) at least 6 beetles with iridescent wing cases.

[4]
b.

In a larger study, a sample of 250 beetles is collected. Use a suitable approximation to find the probability that the number of beetles with iridescent wing cases in this sample is more than 60.

[5]
Markscheme

2.4 Probability Distributions Questions

  1. A Level
  2. /Maths
  3. /2.4 Probability Distributions

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.

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