2025 MI P2 Q7

2025 MI P2 Q7

8 marks

A deck of \(12\) cards consists of \(2\) gold cards and \(10\) silver cards. The cards are identical other than their colours. In a game, three cards are drawn from the deck of cards at random without replacement. The number of gold cards drawn is denoted by \(G\).

  1. Explain the significance of stating that the cards are identical other than their colours.[1]
  2. Show that \(\mathrm{P}(G=2) = \frac{1}{22}\) and find the probabilities of all other possible combinations of the cards drawn.[4]

A gold card is worth \(4\) points while a silver card is worth \(1\) point. The score \(X\) is the sum of the points of each of the three drawn cards.

  1. Using your answers in part (ii), find the probability distribution of \(X\).[2]
  2. If the player of the game wins \(\$10x\) for a score of \(x\) points, what is the expected winnings of the player?[1]

Solution:

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Answer:(i) Each remaining card is equally likely to be selected. (ii) \(P(G=0)=\frac6{11},P(G=1)=\frac9{22},P(G=2)=\frac1{22}\) (last value shown). (iii) \(X=3,6,9\) with those respective probabilities. (iv) 45 dollars.

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