Question

A student has the following grades: 86, 80, 79, 85, 70. Find the standard deviation of the grades.
1) 40.5
2) 1640.5
3) 5.69
4) 32.4

Answer 1

\[sd = \sqrt{\frac{\sum_{}(x-\bar x)}{n-1}}\]
for a sample

Answer 2

but the choices correspond to population sd :) which is /N

3