Question

A student has the following grades: 80, 76, 78, 83, 83. Find the variance of the grades.
1) 2.8
2) 7.6
3) 4.2
4) 0

Answer 1

\[mean = (80+76+78+83+83)/5\]
\[mean = 80\]
Now you find the variance:
\[var = \sum((x_i-mean)^2)/N\]
\[var = (0+16+4+9+9)/5\]
\[var = 38/5 = 7.6\]