Answer
See below.
Work Step by Step
The mean of $n$ numbers is the sum of the numbers divided by $n$.
The range is the difference between the largest and the smallest data value. The standard deviation of $x_1,x_2,...,x_n$ is (where $\overline{x}$ is the mean of the data values): $\sqrt{\frac{(x_1-\overline{x})^2+(x_2-\overline{x})^2+...+(x_n-\overline{x})^2}{n}}$.
Hence here the mean is: $\frac{7+4+6+8+5+9+5+7}{8}=6.375$
Hence here the range is: $9-4=5$, and the standard deviation is: $\sqrt{\frac{(7-6.375)^2+(4-6.375)^2+...+(8-6.375)^2}{8}}\approx1.685$
