Cumulative Distribution Functions for Discrete Random Variables

You can use a CDF to calculate the probability that a random variable is less than or equal to some real number. Learn how this works in the discrete case.

[mutkhaa]

I was kinda confused with the example given above....
For instance,
For 3<= t < 4, P( X<=t) = (1 + 2)/16, but shouldn't it be ' 2<=t <4'?
Also you've given P(X<= T) = 1 WHEN t>=8 but can you have any sum of a two 4 faced dice ... confused if I didn't get the logic behind it or you are mistaken?
waiting for the reply!!!