Question on probablity

[mchidrawar]

I am generating a set of 10000 top elements from x elements every half hour. At the end of the day i will be having 48 such set. After that i am finding out the top 1000 elements from this all 48 such sets.
What is the probability of missing an element which should have come as top 1000?


I am doing this on two machine with and at the end i will be having two sets of 1000 element. Then finding the top 1000 among these 2000. What is the probability of missing element which should have been counted here?

 

[tkhunny]

Let's see if I get this.

You have 48 sets of size 'x'.
You sort each of these sets and pick the top 10,000.
You then take the top 1000 from the 48000 elements you have selected.
You wonder if there is some nonzero probability that the top 1000 from the total failed to be selected by the top 10,000 from each set?

In other words, some element would have to rank 10,001 (or lower) in the individual selections, but somehow rank 1,000 (or higher) in the total selection?

Zero.