MHB Probability of drawing a 10 on the 4th ball?

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The discussion revolves around calculating the probability of drawing a 10 on the 4th ball from an urn containing 10 balls numbered 1 to 10, given that the 4th ball is larger than the first three drawn. Participants emphasize the use of conditional probability and Bayes' Theorem to approach the problem. The probability of the fourth ball being a specific number, such as 10, is linked to the outcomes of the previous draws. The conversation highlights the need to consider the arrangement of the first three balls in relation to the fourth ball's value. Understanding the underlying principles of conditional probability is crucial for solving this problem effectively.
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Hello, I have this question, I need some help with it.

In an urn there are 10 balls marked with the numbers 1-10.
4 balls are being chosen randomly without replacement.
It is known that on the 4th ball that was taken out, there was a number which was larger than the number on any of the previous 3 balls taken.
What is the probability that on the 4th ball the number was 10 ?

I thought of conditional probability, the intersection should be in my opinion:

(9/10)*(8/9)*(7/8)*(1/7)

I am not sure it's right and anyway I don't know what to do with the probability of the 4th being larger than the other 3...

thanks !
 
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Hello, Yankel!

This is Conditional Probability.
Are you familiar with Bayes' Theorem? .$P(A\,|\,B) \;=\;\dfrac{P(A \wedge B)}{P(B)}$
If not, it is useless to solve the problem for you.
In an urn there are 10 balls marked with the numbers 1 - 10.
4 balls are being chosen randomly without replacement.
It is known that the 4th ball had a number larger than the number on any of the previous 3 balls.
What is the probability that on the 4th ball the number was 10 ?
 
Yankel said:
In an urn there are 10 balls marked with the numbers 1-10.
4 balls are being chosen randomly without replacement.
It is known that on the 4th ball that was taken out, there was a number which was larger than the number on any of the previous 3 balls taken.
What is the probability that on the 4th ball the number was 10 ?
Let us suppose that $K$ is the value of the fourth ball that is greater than any of the first three drawn. Clearly $K=4,~5,\cdots,10$.
It should be clear that $\mathcal{P}(K=4)=\dfrac{3!\cdot 6!}{10!}$. Yes or NO?

What is $\mathcal{P}(K=n)$ for $n=5,~6,\cdots,10~?$
 
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