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

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Question 23

A telecommunications engineer monitors the reliability of a satellite link. Under specific atmospheric conditions, the probability of a data packet being lost during transmission is 0.15.

a.

State two assumptions required to model the number of packets lost in a sequence of n n\,n transmissions using a binomial distribution.

[2]
b.

Using this model, find the probability that exactly 4 packets are lost in a random sequence of 18 transmissions.

[2]
c.

Calculate the mean and the variance of the number of packets lost in a sequence of 160 transmissions.

[2]
d.

A link is classified as 'unstable' if more than 30 packets are lost in a sequence of 160 transmissions.

Using a suitable approximation, find the probability that the link will be classified as 'unstable'.

[4]

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

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