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PEAMCQModerate

2025 PEA Q12

Two fair coins. AA: head on first coin. CC: head on second coin. DD: coins match. GG: two heads. Which statement is false?

Reveal answer and solution

Answer

A

Solution

  1. 1

    P(A)=P(C)=P(D)=1/2P(A) = P(C) = P(D) = 1/2, P(G)=1/4P(G) = 1/4.

  2. 2

    \begin{itemize}[leftmargin=*]

  3. 3
    • AG={HH}A\cap G = \{HH\}, P=1/4P = 1/4. P(A)P(G)=1/81/4P(A)P(G) = 1/8 \ne 1/4. Not independent.
  4. 4
    • AD={HH}A\cap D = \{HH\}, P=1/4P = 1/4. P(A)P(D)=1/4P(A)P(D) = 1/4. Independent.
  5. 5
    • CD={HH}C\cap D = \{HH\}, P=1/4P = 1/4. P(C)P(D)=1/4P(C)P(D) = 1/4. Independent.
  6. 6
    • AC={HH}A\cap C = \{HH\}, P=1/4=P(A)P(C)P = 1/4 = P(A)P(C). Independent.
  7. 7

    \end{itemize}

  8. 8

    Hence the FALSE statement is (B): AA and GG are not independent (the question asks for the false claim).

Answer structure / marking notes

Note that GAG \subset A, so AA and GG cannot be independent unless GG is trivial.

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Content note

Imported from public/resources/isi/msqe/solutions/pea/2025/ISI_MSQE_PEA_2025_Solutions.tex. Question wording is retained from the available local TeX source; incomplete option blocks or ambiguous source status are flagged for review.