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Distribution of a finite random variable

Question 1 of 8

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The sample space \(S\) contains the ordered outcomes of a finite 2-stage experiment

At the first stage, the possible outcomes are absent, present. Their numerical codes, in the same order, are 0, 1

At the second stage, the possible outcomes are absent, present. Their numerical codes, in the same order, are 0, 1

The exact probabilities of the ordered outcomes are given below. Outcomes from successive stages remain ordered

The listed probabilities are for the ordered outcomes
Ordered outcomeExact probability
(absent, absent)4/15
(absent, present)1/3
(present, absent)1/3
(present, present)1/15

Define \(X\) as the number of stages whose outcome is absent

The possible values of \(X\) are \(\{0,\,1,\,2\}\)

(a)1 mark

Which option gives the outcome-to-value mapping required by the definition of \(X\)?

(b)2 marks

Complete the missing entries in the distribution of \(X\)

Complete the missing entries
Value of XFrequency
0?
12
2?
(c)2 marks

What is \(Pr(X\in \{2\})\)? Give an exact fraction or a terminating decimal when possible

Format: exact fraction