Answer
$\approx4.27$
Work Step by Step
The mean of $n$ numbers is the sum of the numbers divided by $n$.
Hence the mean: $\frac{13+15+13+18+13+14+23+20+20+24}{10}=17.3$
The standard deviation of $x_1,x_2,...,x_n$ is (where $\overline{x}$ is the mean of the data values): $\sqrt{\frac{(x_1-\overline{x})^2+(x_2-\overline{x})^2+...+(x_n-\overline{x})^2}{n-1}}$.
Hence here the the standard deviation is: $\sqrt{\frac{3(13-17.3)^2+(14-17.3)^2+(15-17.3)^2+(18-17.3)^2+2(20-17.3)^2+(23-17.3)^2+(24-17.3)^2}{10-1}}\approx4.27$
