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2.4.4 Mean and variance of the binomial (A-level only)

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Question 29

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]

2.4.4 Mean and variance of the binomial (A-level only) Questions

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  3. /2.4.4 Mean and variance of the binomial (A-level only)