The GATE Grind

GATE 2023 PI – Question 14

Engineering Mathematics · Probability and Statistics · 1 mark · Multiple choice

Three unbiased coins are tossed. Given that at least two outcomes are tails, find the probability that all three are tails.

  1. 1/8
  2. 1/4
  3. 1/3
  4. 1/2

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Show answer and explanation

Correct answer: (B) 1/4

Explanation

The conditioning event consists of TTH, THT, HTT and TTT, all equally likely. Only TTT has three tails. Therefore the conditional probability is **1/4, B**.

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