GMAT Quantitative Reasoning Practice Test 2

The first toss will be either heads or tails. The probability that the result on the second toss is identical to the first is $\frac{1}{2}$ . The probability that the result on the third toss is identical to that of the second is also $\frac{1}{2}$ . The total probability is, therefore, $\frac{1}{2}\times \frac{1}{2}=\frac{1}{4.}$