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Identical results in tosses

ProbabilityEasy

A fair coin is tossed times, independently. What is the probability that all results are the same (all heads or all tails)? Give a fraction in lowest terms.

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A whole number, a decimal, a fraction like 3/8 or a percent.

Hint

Count the favorable sequences and compare with the total number of equally likely sequences.

Solution
  1. There are equally likely sequences of results.
  2. Exactly of them are constant: all heads and all tails.
  3. The probability is , which reduces to .
  4. The answer is .

Answer: