Multiple choice

When a fair coin is tossed thrice, the probability of obtaining head at most twice is

  1. $\dfrac{1}{8}$
  2. $\dfrac{5}{8}$
  3. $\dfrac{7}{8}$
  4. $\dfrac{3}{8}$
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C Correct answer
Explanation

The probability of getting heads at most twice is 1 minus the probability of getting heads three times. P(3 heads) = (1/2)^3 = 1/8. So, 1 - 1/8 = 7/8.

AI explanation

Using the complementary event approach, the probability of getting heads at most twice is 1 minus the probability of getting exactly 3 heads. The probability of getting exactly 3 heads is (1/2)^3 = 1/8. Therefore, the required probability is 1 - 1/8 = 7/8.

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