Given $X=\text{the number of heads in 5 dice throws}$. Here $X$ is a "single" RV and the outcomes are mappes to some distribution.
However, i get confused when $X=\{ X_1,X_2,...,X_n \} $ is called "a sample of size $n$, or of equally distrubuted RV's. What does that mean? Could it mean:
a) something like $X_1=\text{the number of heads in 5 dice throws in exp. 1}$, $X_2=\text{the number of heads in 5 dice throws exp. 2}$ and so on
b) something like $X_1=\text{the number of heads in 5 dice throws in some exp. }$, $X_2=\text{number of people with weight x in some further exp. }$ and so on
What is the meaning of $n$ in this context: does it "measure" $n$ diferent attributes to observe or indicate just $n$ repitions of the experiment?