Edexcel S2 2016 June — Question 2

Exam BoardEdexcel
ModuleS2 (Statistics 2)
Year2016
SessionJune
TopicApproximating the Binomial to the Poisson distribution
TypeFind parameter from Poisson probabilities

2. The random variable \(X \sim \mathrm {~B} ( 10 , p )\)
    1. Write down an expression for \(\mathrm { P } ( X = 3 )\) in terms of \(p\)
    2. Find the value of \(p\) such that \(\mathrm { P } ( X = 3 )\) is 16 times the value of \(\mathrm { P } ( X = 7 )\) The random variable \(Y \sim \operatorname { Po } ( \lambda )\)
  1. Find the value of \(\lambda\) such that \(\mathrm { P } ( Y = 3 )\) is 5 times the value of \(\mathrm { P } ( Y = 5 )\) The random variable \(W \sim \mathrm {~B} ( n , 0.4 )\)
  2. Find the value of \(n\) and the value of \(\alpha\) such that \(W\) can be approximated by the normal distribution, \(\mathrm { N } ( 32 , \alpha )\)