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4.1.1 Probability (A-level only)

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Question 83

A quality assurance manager at a high-precision fabrication facility is analyzing the occurrence of component defects across different work shifts.

Event S S\,S is defined as a component being produced during the night shift.

Event M M\,M is defined as a component having a mechanical defect.

The results of a random audit are summarized in the following table of probabilities:

MM′S0.080.32S′0.040.56\begin{array}{|c|c|c|} \hline & M & M' \\ \hline S & 0.08 & 0.32 \\ \hline S' & 0.04 & 0.56 \\ \hline \end{array}SS′​M0.080.04​M′0.320.56​​
a.

A component is selected at random from the audit.

(i) Find P(S)P(S)P(S).

(ii) Find P((S∩M)′)P((S \cap M)')P((S∩M)′).

(iii) Find P(M∣S′)P(M | S')P(M∣S′).

[4]
b.

Determine whether the events S S\,S and M M\,M are independent. Fully justify your answer.

[2]

4.1.1 Probability (A-level only) Questions

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