a coin has 2 sides....heads and tails....so the probability of it landing on heads is 1/2....the same as the probability of it landing on tails is 1/2.
Therefore, the probability of it landing on heads on 1 coin flip is 1/2.
so the probability of it landing on heads on 3 coin flips is :
1/2 * 1/2 * 1/2 = 1 / 8 <==