Hint. In the experiment where a fair coin is tossed two times and a pair of faces is observed, we usu- ally assume the sample space S = {(H, H), (H, T), (T, H), (T, T) } is equally likely, that is, the probability of observing each pair is 1/4. Recall the graph in the slide 3 from Ch2 ppt. A fair coin implies the probability Probability of Observation of a Head 1.0 0.9 0.8 Probability 0.6 0.5 0.4 100 200 300 400 500 # of flips of observing the head will converge to 0.5 as the number of tosses increases. What will be the probability of observing a pair of two heads when a coin is not fair