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2 Statistics

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Question 298

A backup system contains three independent components. Their probabilities of working on demand are 0.95, 0.90 and 0.80. The system works if at least two components work.

a.

Find the probability that the system works.

[4]
b.

In 1000 independent demands, find the expected number on which the system fails.

[2]
c.

State one reason why independence may be an unsuitable assumption for the components.

[1]
Markscheme

2 Statistics Questions

  1. A Level
  2. /Maths
  3. /2 Statistics

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