Need help understanding litecoin mining calculator

[Bogart]

I'm having some trouble understanding the numbers I'm seeing on litecoinpool's mining calculator.

http://www.litecoinpool.org/calc?hashrate=325&difficulty=22.36096172

Putting in my hashrate and current difficulty, the graph puts 50% probability of finding a block at about 2.4 days.

But the numbers shown in the Expected Rewards section don't seem to match.  If I'm finding a block every 2.4 days on average, I would expect to earn 145.833 LTC at 7 days, but it shows 102.332 LTC.

Why the difference?

[DeathAndTaxes]

That type of graph is a CDF (continual distribution function).  It isn't saying what you think it is saying.  It isn't saying you will find a block on average every 2.4 days.  It is a continual distribution function.  It is backwards looking.  Say you mined a infinite number of blocks and recorded the amount of time each block took.  You would find that based on the values you used that 50% of them took longer than 2.4 days and 50% took less than 2.4 days.  You can't simply take 2.4 double it and say 100% of blocks will be found in 4.8 days.  Mining doesn't work that way.