Find the constant K?
I know how to find K, if there is only one "k" in the question and the rest are given number. I know that all the x value are add upto 1.
But in this question, I don't know how to start.
One thing I know is $\Sigma(x)=1(k)+2(2k)+3(3k)+4(4k)+5(5k)$
Does this help to find the constant k?
Please help me "Find the constant k"
Appreciate your help.
Best Answer
You are confused. It's pretty fine. Please note that $X=i$ means the event that X equals i. So, let me interpret the table for you.
Important: By Unitarity of probability, the probability of $Pr({\text{$X$ = 1,2,3,4 or 5}})=1$.
$X=1, X=2, X=3, X=4, X=5$ are five mutually exclusive events in the sample space, and there are no other events. So, $$Pr(X=1,2,3,4,5)=\sum_{i=1}^5Pr(X=i)=k+2k+3k+4k+5k = 15k$$
So, what's $k$?