There are \(2^3=8\) possible outcomes after tossing a fair coin fairly 3 times. The 8 possible outcomes are: TTT, HTT, THT, TTH, HHT, HTH, THH, HHH. Exactly 2 of 8 possible outcomes result in \(\mathbf{3}\) of the same faces showing up. They are TTT and HHH. Each has a probability of \(\dfrac{1}{8}\) of happening and since either showing up satisfactorily addresses the criterion for success, the probability as requested \(=2 \times (\dfrac{1}{8})=\dfrac{1}{4}=.25\) \(=25 \%\).