Multiple choice

Find the probability of getting $2$ or $3$ tails when a coin is tossed four times.

  1. $\dfrac{7}{16}$
  2. $\dfrac{9}{16}$
  3. $\dfrac{5}{8}$
  4. $\dfrac{5}{16}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total outcomes = 2^4 = 16. Favorable: 2 tails (4C2 = 6) or 3 tails (4C3 = 4). Total favorable = 6 + 4 = 10. Probability = 10/16 = 5/8.

AI explanation

Using the binomial distribution formula, the probability of getting exactly r tails in 4 tosses is 4Cr multiplied by (1/2) to the power of 4. The probability of getting 2 tails is 6/16 and the probability of getting 3 tails is 4/16. Adding these probabilities gives 10/16, which simplifies to 5/8. The result is 5/8.

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