Suppose there are 4 cups, and a ball is under one of these cups. Assuming it has equal chance of bei

Anahi Jensen

Anahi Jensen

Answered question

2022-05-21

Suppose there are 4 cups, and a ball is under one of these cups. Assuming it has equal chance of being at under any cup, the probability of it being under cup A is 25% correct?
Now assume after 1000 observations, I notice 90% of the times, ball is under cup A.
Now, if I have to predict where the ball is, I’d say it has 90% probability of being under A. Does that make sense?
If cup D is removed, how should I change my estimate? I know it must increase, since if I remove B,C and D, probability raises to 100%.
Thanks you all in advance!

Answer & Explanation

Dominique Holmes

Dominique Holmes

Beginner2022-05-22Added 10 answers

After 1000 observations, you notice that 90% of the time, the ball is under Cup A. However, as Doug M mentioned, after 10,000 times, your probability would become lower.
So, instead of thinking of Cup A as one cup, think of it as many different cups. I'll show you what I mean.
100 90 = 10
10 / 3 = 3. 3 ¯
Therefore, Cups C, D, and E have a theoretical probability of 3. 3 ¯ of having the ball.
Therefore, Cup A is made up of 90 3. 3 ¯ or 27 separate cup A's.
Thus, there are currently 27 Cup A's which you consider to be your one cup A.
So, 27 A + B + C + D = 100
If you remove Cup D, which makes up 3. 3 ¯ of the percentage, you have to add another cup A.
28 A + B + C = 100
Follow this reasoning, and you will obtain your answer.

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