First of all, we know that the coin has two sides - head and tail, do
P(landing on head) first time:
1/2
P(landing on head) second time:
1/2
P(landing on tail) last flip:
1/2. As a result, the probability that you'll get heads on the first two flips and tails on the last flip is 1/2×1/2×1/2=1/8. Hope it help!
