Which of the Following Is the Correct Formula for Calculating $\sum \mathbf { X } + n$

Multiple Choice

Which of the following is the correct formula for calculating the mean?

A) $\sum \mathbf { X } + n$
B) $\sum \mathrm { X } / \mathrm { X }$
C) $\sum \mathrm { X } / n$
D) $\sum \mathrm { X } + \mathrm { X }$