Urn contains 20 balls numbered from 1 to 10 (two balls for each number) Urn contains 20 balls numbered from 1 to 10 (two balls for each number). 4 balls are picked without replacement. What's the probability of getting 4 distinct (different numbers) balls?
What I did is: 20/20 * 18/19 * 16/18 * 14/17
But I don't know if it is right or not

Community wiki answer so the question can be marked as answered:
Your calculation is correct.
