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8 marksDiscrete Random Variables

CAPE Applied Mathematics Unit 2 · 2015 · Paper 2 · Question 3(a)(ii)

Twenty per cent of bolts manufactured by a factory are defective.

If X represents the number of defective bolts manufactured by the factory, determine the SMALLEST value of n for which the ratio of the standard deviation of X to the mean of X is less than 0.1.

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Other parts of this question

  1. 3(a)(i)Determine the probability that in a random sample of 15 bolts, more than one is defective.[4 marks]
  2. 3(b)If X ~ Bin(500, 0.005), use a suitable approximation to find P(X ≤ 2).[5 marks]
  3. 3(c)If X ~ Po(20), use a suitable approximation to find P(X ≤ 25).[5 marks]
  4. 3(d)If X follows a geometric distribution with probability 0.3, determine the probability that X is less than 4.[3 marks]

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