CAIE S1 2017 November — Question 3

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2017
SessionNovember
TopicDiscrete Probability Distributions
TypeSequential trials until success

3 A box contains 6 identical-sized discs, of which 4 are blue and 2 are red. Discs are taken at random from the box in turn and not replaced. Let \(X\) be the number of discs taken, up to and including the first blue one.
  1. Show that \(\mathrm { P } ( X = 3 ) = \frac { 1 } { 15 }\).
  2. Draw up the probability distribution table for \(X\).