A box contains 5 red, 3 green and 4 blue balls. A boy is allowed to take away two balls from the box. What is the probability that the two balls are red?

  • A \(\frac{5}{33}\)
  • B \(\frac{5}{36}\)
  • C \(\frac{103}{132}\)
  • D \(\frac{31}{36}\)
waec 2001mathematics

The correct answer is A. \(\frac{5}{33}\)

Total number of balls = 5 + 3 + 4 

= 12 balls

P(first ball is red) = \(\frac{5}{12}\)

P(second ball is red) = \(\frac{4}{11}\)

\(\therefore\) P(both balls are red) = \(\frac{5}{12} \times \frac{4}{11}\)

= \(\frac{5}{33}\)

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