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NDA 2 2025 Maths, question 112

Topic: Probability

Q112

In a throw of three dice, what is the probability of getting one prime number, one composite number and one number which is neither prime nor composite?

  1. (a) 1/21/2
  2. (b) 1/31/3
  3. (c) 1/41/4
  4. (d) 1/61/6Correct answer

Solution.

Answer: (d) 1/61/6

  1. The prime faces are 2,3,5; composite faces 4,6; and 1 is neither.
  2. Choose one from each and assign them to the three dice: 3×2×1×3!=36 favourable outcomes out of 6³=216.
  3. The probability is 1/6.