(i) To find the probability of obtaining exactly 1 head and 2 tails, consider the scenarios: HTT, THT, and TTH.
For HTT: \(P(H) = \frac{2}{3}, P(T) = \frac{1}{3}\) for Coin A and \(P(T) = \frac{3}{4}\) for Coin B.
\(P(HTT) = \frac{2}{3} \times \frac{1}{3} \times \frac{3}{4} = \frac{2}{12} = \frac{1}{6}\).
For THT: \(P(T) = \frac{1}{3}, P(H) = \frac{2}{3}\) for Coin A and \(P(T) = \frac{3}{4}\) for Coin B.
\(P(THT) = \frac{1}{3} \times \frac{2}{3} \times \frac{3}{4} = \frac{2}{12} = \frac{1}{6}\).
For TTH: \(P(T) = \frac{1}{3}, P(T) = \frac{1}{3}\) for Coin A and \(P(H) = \frac{1}{4}\) for Coin B.
\(P(TTH) = \frac{1}{3} \times \frac{1}{3} \times \frac{1}{4} = \frac{1}{36}\).
Total probability: \(\frac{1}{6} + \frac{1}{6} + \frac{1}{36} = \frac{12}{36} + \frac{1}{36} = \frac{13}{36}\).
(ii) The probability distribution table is:
| x | 0 | 1 | 2 | 3 |
|---|
| P | \(\frac{3}{36}\) | \(\frac{13}{36}\) | \(\frac{16}{36}\) | \(\frac{4}{36}\) |
(iii) The expectation \(E(X)\) is calculated as:
\(E(X) = 0 \times \frac{3}{36} + 1 \times \frac{13}{36} + 2 \times \frac{16}{36} + 3 \times \frac{4}{36}\).
\(E(X) = \frac{0}{36} + \frac{13}{36} + \frac{32}{36} + \frac{12}{36} = \frac{57}{36} = \frac{19}{12} \approx 1.58\).