Homework 4, Problem #2

[yasmine]

On problem #2 question #2, I think I did the formula correctly, but this is still puzzling to me. Since you are looking for pr[x>(or equal to) 1] once you do the whole formula is that just the answer? That would give you 0.32274. Or then do you take that and do 1-0.32274 to give you 0.67726?

[Taeho Kim]

First of all, this is not about Pr [X>=1].
"1" should be excluded from our interest.

Now, think about the all possible outcomes we are interested in.
These are too many, so that we have to repeat the formula too many times.
However, outside of these possible outcomes, there are only a few outcomes.
So, find out the probabilities for those outside outcomes and use the complement rule.