Hi, I need some help with summation, I'm missing it in class today because I'm sick. The question I'm working on is:

Evaluate $\displaystyle \sum\left(\begin{array}{cc}n\\i\end{array}\right)* \frac{1}{2^n}$.

If $\displaystyle \sum\left(\begin{array}{cc}n\\i\end{array}\right)= 2^n$

would that mean $\displaystyle \sum\left(\begin{array}{cc}n\\i\end{array}\right)* \frac{1}{2^n}=\sum 1=n$?