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There are two groups, A and B, of students in German language class. Each group consists of $15$ students. In the tables, down each column, a student’s ID and grade from the mid-year’s grade report are listed. The students are evaluated according to the grading scale from $1$ to $5$, while $1$ is the best grade and $5$ is the worst one. Calculate the coefficient of variation of grades for each group and determine in which group the grades are more balanced. I.e. choose the name of the group with more balanced grades and with the correct coefficient of variation ($\mathrm{\%}$) of grades. The value of the coefficient of variation is rounded to two decimal places. $$\begin{array}{|ccccccccc|}\hline \mathbf{\text{A -- students}}& 1& 2& 3& 4& 5& 6& 7& 8\\ \mathbf{\text{Grade}}& 2& 2& 2& 2& 3& 2& 1& 2\\ \\ \mathbf{\text{A -- students}}& 9& 10& 11& 12& 13& 14& 15& \\ \mathbf{\text{Grade}}& 2& 1& 3& 1& 3& 2& 3& \\ \hline\end{array}$$ $$\begin{array}{|ccccccccc|}\hline \mathbf{\text{B -- students}}& 1& 2& 3& 4& 5& 6& 7& 8\\ \mathbf{\text{Grade}}& 2& 1& 1& 2& 2& 3& 1& 2\\ \\ \mathbf{\text{B -- students}}& 9& 10& 11& 12& 13& 14& 15& \\ \mathbf{\text{Grade}}& 2& 1& 2& 1& 1& 1& 1& \\ \hline\end{array}$$