Cara computes the mean and variance for the set \{87, 46, 90, 78, 89\}. She finds the mean to be 78. Her steps for finding the variance are shown below.
[tex]\[
\begin{array}{l}
\sigma^2 = \frac{(87-78)^2 + (46-78)^2 + (90-78)^2 + (78-78)^2 + (89-78)^2}{5} \\
\sigma^2 = \frac{(9)^2 + (-32)^2 + (12)^2 + 0^2 + (11)^2}{5} \\
\sigma^2 = \frac{81 + 1024 + 144 + 0 + 121}{5} \\
\sigma^2 = \frac{1370}{5} = 274
\end{array}
\][/tex]
What is the first error Cara made in computing the variance?