Probability Theory

JKSSB Finance Accounts Assistant · Statistics · 15 practice questions with answers and explanations: 3 Easy, 6 Medium, 6 Hard.

Sample questions

Sample Easy question 1

The probability of an impossible event is:

  1. 1
  2. 0.5
  3. 0
  4. −1
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Answer: C. Probabilities range from 0 (impossible) to 1 (certain); they are never negative.

Sample Medium question 2

A fair die is rolled once. The probability of getting a number greater than 4 is:

  1. 1/3
  2. 1/2
  3. 2/3
  4. 1/6
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Answer: A. Numbers greater than 4 are 5 and 6: 2 of 6 = 1/3.

Sample Hard question 3

A bag has 3 red and 5 blue balls. Two balls are drawn one after another without replacement. The probability that both are red is:

  1. 3/28
  2. 9/64
  3. 3/8
  4. 1/4
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Answer: A. P = 3/8 × 2/7 = 6/56 = 3/28. (9/64 would be the answer with replacement.)

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