In the binomial function, negative binomial function, poissondistribution, I dont know what to do when we need to find avariable X. For example, If X is exactly at 0, 1 , 2, etc. Then Iknow that we only need to apply the formula and calculate it.However, in some cases like X <= 2, X >= 5, X > 4, etc,then I do not know how to calculate that X and how to apply theformula. Ex: If P( X >= 4) = 1 - P(X <= 3) and for X <= 3,we will calculate the sum of X = 0, X = 1, X = 2, X = 3. How todefine when to use 1 - P(X <= 3) or how P(X = 4) = P(X <= 4)- P(X <= 3). It really hard for me to understand this concept.Is there any formula or any way to define it so you know when tosubtract, or when to add it together? Thank you.
