Ok, I'm sure this is simple, yet I'm confused.
Lets say my goal is to obtain an average concentration C=N/V so I take a number of N and V readings with errors:
$N_1=50\pm2, V_1=100\pm4$
$N_2=102\pm2, V_2=205\pm4$
$N_3=52\pm2, V_3=99\pm4$
Now if I remember correctly the standard deviation s propagates to C with
$s_{C} = \sqrt{(\frac{\partial{C}}{\partial{N}}s_N)^2+(\frac{\partial{C}}{\partial{V}}s_V)^2}$
But now how do I get the average with a meaningful total standard deviation? Or should I approach this in a different way altogether?