Explanation:
a) The probability that Stephen wins can be estimated by dividing the number of times he wins by the total number of matches:
P(Stephen wins) = 11/27 = 0.407 (or 40.7%)
b) The probability that Natasha wins can be estimated by subtracting the probability of Stephen winning from 1:
P(Natasha wins) = 1 - P(Stephen wins) = 1 - 0.407 = 0.593 (or 59.3%)