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In a set of 30 game cards, 17 are white and rest are green. 4 white and 5 green are marked IMPORTANT. If a card is chosen randomly from this set, what is the possibility of choosing a green card or an ‘IMPORTANT’ card?

  • A.13/30
  • B.22/30
  • C.17/30
  • D.9/13

Answer: C

Of the 30 cards, 17 are white and 13 green. Nine are marked IMPORTANT: 4 white and 5 green.

Adding the two counts directly would double-count the 5 green IMPORTANT cards, so use the addition rule:

\[ P(G \cup I) = P(G) + P(I) - P(G \cap I) \]

\[ = \frac{13}{30} + \frac{9}{30} - \frac{5}{30} = \frac{17}{30} \]

Equivalently, count the 13 green cards plus the 4 white IMPORTANT ones: \( \tfrac{17}{30} \).

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