I would like to use the probabilty function and am having some difficulty.

I have a lower limit 0 and an upper limit 1400 an array1 with a set of 21 values and another array2 with a set of 21 probability values. The individual probability values are each 1/count(array1).

I'm finding that if I just have 10 or 20 values it works fine, however, if I have 21 it appears that the sum of the probability values doesn't add up to exactly 1

Or something else is going on. Attached is a sheet that started with 21 values and didn't work. I then copied this to the right. I deleted one set of values from the left side and it works with an even number of 20. However, when I do the same thing on the right side it doesn't even though this should be the same thing????

When I just do an example the thing tends to work, but, when I go with real numbers it tends not to.

Any ideas, thanks in advance!