Edexcel FS1 Specimen — Question 2

Exam BoardEdexcel
ModuleFS1 (Further Statistics 1)
SessionSpecimen
TopicBinomial Distribution
TypeFinding binomial parameters from properties

  1. A call centre routes incoming telephone calls to agents who have specialist knowledge to deal with the call. The probability of a caller, chosen at random, being connected to the wrong agent is p.
The probability of at least 1 call in 5 consecutive calls being connected to the wrong agent is 0.049 The call centre receives 1000 calls each day.
  1. Find the mean and variance of the number of wrongly connected calls a day.
  2. Use a Poisson approximation to find, to 3 decimal places, the probability that more than 6 calls each day are connected to the wrong agent.
  3. Explain why the approximation used in part (b) is valid. The probability that more than 6 calls each day are connected to the wrong agent using the binomial distribution is 0.8711 to 4 decimal places.
  4. Comment on the accuracy of your answer in part (b).