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

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Question 12

A factory produces a large batch of glass beads, of which 8% are found to have minor surface imperfections. A random sample of 50 beads is selected and the number of imperfect beads is recorded.

a.

Find the probability that there are at most 5 imperfect beads in this sample.

[2]
b.

A second random sample of 50 beads is selected and the number of imperfect beads is recorded.

Using a Poisson approximation, estimate the probability that the total number of imperfect beads in the combined sample of size 100 is fewer than 11.

[3]

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)