Theoretical Probability

Definition of Theoretical Probability

It is the likeliness of an event happening based on all the possible outcomes. The ratio for the probability of an event 'P' occurring is P (event) = number of favorable outcomes divided by number of possible outcomes.

Examples of Theoretical Probability

From the letters A, E, I, O, U the theoretical probability of selecting the letter E is 1/5

Video Examples: Finding Theoretical Probability

Solved Example on Theoretical Probability

Ques: A coin is tossed on a standard 8X8 chessboard. What is the theoretical probability that the coin lands on a black square?

  • A. 0.5
  • B. 0.25
  • C. 0.42
  • D. 0.6

Correct answer: A


  • Step 1: Theoretical probability = number of favorable outcomes / number of possible outcomes.
  • Step 2: The probability of the coin lands on the black square is 32.
  • Step 3: Total number of outcomes = 64.
  • Step 4: P (event) = 32/64
  • Step 5: = 1/2 = 0.5
  • Step 6: The theoretical probability that the coin lands on a black square is 0.5.

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