Amit;

Ok, in 2010 there were 104 days with quakes so far so I set up an array 104 days long. I placed each quake in the proper array element. There were 64 of them.

Then I picked 9 days at random and checked each one for a quake using a 3 day window centered on the selected day. If the was a quake in the window I added one to the hit total.

Once all 9 dates were checked, the number of hits was added to the hit array which contained array elements from 0 to 9.

I repeated this 10,000 times. The results are as follows:

HITS TOTAL
0 -- 0
1 -- 1
2 -- 7
3 -- 60
4 -- 236
5 -- 845
6 -- 2013
7 -- 3093
8 -- 2748
9 -- 997

As you can see, 7 is the most common value and there are a lot of 9.

Satisfied?

Roger