Multiple choice

The probability of obtaining at least one head when we toss n unbiased coins is

  1. $\dfrac{C_{0}^{n}}{2^{n}}$
  2. $\dfrac{1-C_{r}^{n}}{2^{n}}$
  3. $1-\dfrac{1}{2^{n}}$
  4. $\dfrac{C_{r}^{n}}{2^{n}}$
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C Correct answer
Explanation

The probability of getting at least one head is 1 minus the probability of getting no heads. The probability of no heads in n tosses is (1/2)^n. Thus, 1 - (1/2)^n.

AI explanation

To find the probability of getting at least one head, we use the complementary event approach by calculating the probability of getting no heads and subtracting it from one. The probability of getting zero heads, which means all tails, when tossing n unbiased coins is 1 divided by 2 raised to the power of n. Therefore, the required probability is 1 minus 1 divided by 2 raised to the power of n.

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