Edexcel S1 2008 June — Question 3

Exam BoardEdexcel
ModuleS1 (Statistics 1)
Year2008
SessionJune
TopicDiscrete Probability Distributions
TypeTwo unknowns from sum and expectation
3. The random variable \(X\) has probability distribution given in the table below.
\(x\)- 10123
\(\mathrm { P } ( X = x )\)\(p\)\(q\)0.20.150.15
Given that \(\mathrm { E } ( X ) = 0.55\), find
  1. the value of \(p\) and the value of \(q\),
  2. \(\operatorname { Var } ( X )\),
  3. \(\mathrm { E } ( 2 X - 4 )\).
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