Supposing that the 14 measurements are respectively labeled as x_1, x_2, and considering those as {38,-82,19,84,-37,93,-31,-73,-50,-65, -31, -85,-48, 57}
[tex]\begin{gathered} \sum ^{14}_{n\mathop=1}\frac{x_i}{50}=(\frac{38}{50}+\frac{-82}{50}+\frac{-37}{50}+\frac{93}{50}+\frac{-31}{50}+\frac{-73}{50}+\frac{-50}{50}+\frac{-65}{50}+\frac{-31}{50} \\ +\frac{-85}{50}+\frac{-48}{50}+\frac{57}{50}) \\ \sum ^{14}_{n\mathop{=}1}\frac{x_i}{50}=\frac{-157}{25} \end{gathered}[/tex]Considering that, every 14 entries in this summation is going to be divided by 50 and added up. Thus,
[tex]\sum ^{14}_{n\mathop=1}\frac{x_i}{50}=\frac{-157}{25}\text{ = -6.28}[/tex]
