2018 VJC J2 MYE P1 Q10

2018 VJC J2 MYE P1 Q10

7 marks
Mid Year Exam

A board of directors consists \(n\) men and \(\left( 10-n \right)\) women, where \(3\le n\le 7\). A committee consisting \(3\) randomly chosen people is to be formed. Let \(W\) be the number of women in the committee.

  1. Show that \(\mathrm{P}\left( W=1 \right)=\frac{n\left( n-1 \right)\left( 10-n \right)}{240}\) and find, in terms of \(n\), the probability distribution of \(W\).[4]
  2. Given \(E\left( W \right)=2.1\), find \(n\).[2]
  3. Hence, find \(\mathrm{Var}\left( W \right)\).[1]

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Answer:(ii) \(3\) (iii) \(\text{Var}\hspace{0.1em}(W) = \frac{49}{100}\)

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