There was no more research before the science exam. As long as you do what you know is right, and occasionally you don't know what you won't, it's all a long play.

Don't be confused about the classification:

Winning probability:

Win three games: (1/3 *1/3 *1/3 * 2/3) *10 = 40/243/10 = C35.

Win four games: (1/3 *1/3 *1/3 *1/3 * 2/3) * 5 =10/243//5 = c 45.

Win five games: (1/3) 5 =1/243/1= c 55 omitted.

Total: 5 1/243

Probability of failure:

Lose three games: (1/3 *1/3 * 2/3 * 2/3) *10 = 80/243.

Lose four games: (1/3 * 2/3 * 2/3 * 2/3 * 2/3 * 2/3) * 5 = 80/243.

Lose five games: (2/3) 5 = 32/243

Total: 192/243

So the probability of winning or losing adds up to exactly 1.

Which one upstairs did it right? Don't mislead others' children.