Answer
See step by step work for answer.
Work Step by Step
i) let E be the event that the outcome s occurs. Then according to Laplace's definition, $P(s)=\frac{|E|}{|S|}$ and since S is a finite sample space as well as $E \subseteq S \Rightarrow 0\leq|E| \leq |S|$,
we obtain $0 \leq P(s)= \frac{|E|}{|S|} \leq 1$
ii) Since according to Laplace's definition there are n equally likely outcome each assigned with a probability $\frac{1}{n}$, it is straightforward that $\sum_{s \in S}p(s)=\sum_{s\in S}\frac{|E|}{|S|}=\sum_{s\in S,|S|=n}\frac{1}{n}=n.\frac{1}{n}=1$