Answer:
0.484
Step-by-step explanation:
Given that:
Alice defeats Carol 50% of the time.
This implies that, the probability of defeating Carol = 0.5
Also the probability of losing to Carol = 1 - 0.5 = 0.5
Similarly, Alice defeats Betty 40% of the time.
The probability of Alice defeating Betty = 0.4 and the probability of losing to Betty = 1 - 0.4 = 0.6
However, in as much as Alice needs to win two consecutive games, the sequence which satisfies this condition are as follows:
Let W represent Win and L represent L.
Then the conditions are WWW, WWL and LWW
Since the outcome of each game is independent of the other games.
Then, the probability that Alice wins two games against Carol CBC is:
Pr(2W - CBC) = (0.5 × 0.4 × 0.5) + ( 0.5 × 0.4 × 0.5) + ( 0.5 × 0.4 × 0.5)
Pr(2W - CBC) = 0.1 + 0.1 + 0.1
Pr(2W - CBC) = 0.3
The probability that Alice wins two games against Betty (BCB) is:
Pr(2W - BCB) = (0.4 × 0.5 × 0.4) + (0.6 × 0.5 × 0.4) + ( 0.4 × 0.5 × 0.6)
Pr(2W - BCB) = 0.08 + 0.12 + 0.12
Pr(2W - BCB) = 0.32
However, the Probability of winning two consecutive games is the result of the addition of the probability of winning two consecutive games in the sequence CBC together with the probability of winning two consecutive games in the sequence of BCB.
i.e.
Pr(2W) = Pr(2W- CBC) + Pr(2W - BCB)
Pr(2W) = 0.3+0.32
Pr(2W) = 0.62
Finally, to calculate the probability that Alice will get $100 if she chooses the sequence CBC is: