A data consists of \( 20 \) observations \( x_{1}, x_{2}, \ldots, x_{20} \). If \( \sum_{i=1}^{20} (x_{i}+5)^{2} = 2500 \) and \( \sum_{i=1}^{20} (x_{i}-5)^{2} = 100 \), then the ratio of mean to standard deviation of this data is:
\( 2:1 \)
\( 3:1 \)
\( 3:2 \)
\( 4:1 \)