Answer:
0.3597 = 35.97% probability that roommate A wins the game and thus does not have to wash the dishes.
Step-by-step explanation:
Independent events:
If two events are independent, the probability of both happening is the multiplication of their probabilities.
Rock-paper-scissors rules:
A player that choose rocks beats one who chooses scissors.
A player that choose paper beats one who chooses rocks.
A player that choose scissors beats one who chooses paper.
Probability that roommate A wins the game and thus does not have to wash the dishes.
3 possible events:
Roommate A - Rocks(21% of the time) and Roommate B - Scissors(18% of the time)
So
Roommate A - Paper(39% of the time) and Roommate B - Rocks(61% of the time).
So
Roommate A - Scissors(40% of the time) and Roommate B - Paper(21% of the time).
So
Probability of roommate A winning:
0.3597 = 35.97% probability that roommate A wins the game and thus does not have to wash the dishes.