There are 5 balls, 2 marked "Yes" and 3 unmarked. Five people draw the balls one by one without replacement. The question asks if the probability that each person draws a "Yes" ball is the same.
2025/4/16
1. Problem Description
There are 5 balls, 2 marked "Yes" and 3 unmarked. Five people draw the balls one by one without replacement. The question asks if the probability that each person draws a "Yes" ball is the same.
2. Solution Steps
Let be the probability that the -th person draws a "Yes" ball.
For the first person, the probability of drawing a "Yes" ball is:
For the second person, we consider two cases:
Case 1: The first person drew a "Yes" ball. Then there is 1 "Yes" ball and 3 unmarked balls remaining, for a total of 4 balls. The probability of the second person drawing a "Yes" ball is . The probability of this case happening is .
Case 2: The first person drew an unmarked ball. Then there are 2 "Yes" balls and 2 unmarked balls remaining, for a total of 4 balls. The probability of the second person drawing a "Yes" ball is . The probability of this case happening is .
Thus, the probability of the second person drawing a "Yes" ball is:
Now, let's check for the third person. We will consider two cases to see if the 3rd person draws a "Yes" ball:
Case 1: Two "Yes" were drawn in the first two draws. The probability of this is
The 3rd person's probability to draw "Yes" is 0 since there are no "Yes" balls left,
Case 2: One "Yes" and one unmarked were drawn in the first two draws. The probability of this is
The 3rd person's probability to draw "Yes" is , so the probability of this case is
Case 3: Two unmarked were drawn in the first two draws. The probability of this is
The 3rd person's probability to draw "Yes" is , so the probability of this case is
Adding the probabilities, we get
In general, the probability of drawing a "Yes" ball is the same for each person, which is .
3. Final Answer
Yes, the probability that each person draws a "Yes" ball is the same.