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A fair coin is tossed 10 times. What is the probability that the first two tosses will yield heads?

1. (1/2)^2
2. {}^{10}C_2 (1/2)^2
3. (1/2)^{10}
4. {}^{10}C_2 (1/2)^{10}

Correct answer: (1/2)^2

Solution

The tosses are independent, so the probability of getting heads on the first two tosses is bd d7 bd. The other 8 tosses are irrelevant to the event described.

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