Look at the first outcome: HHH. Since the probability of heads is 0.75 = 3/4, the probability of getting the sequence HHH of three heads in a row is (3/4)(3/4)(3/4) = 27/64.
Similarly, the probability of HHT is (3/4)(3/4)(1/4) = 9/64, since the probability of tails is 0.25 = 1/4.
Continue in this manner to obtain the probabilities of all the outcomes.
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