What is the mean of 20, 70, 30, 25, and 5?

Mean is given as: 

 Mean= $\frac{\mathrm{Sum} \mathrm{of} \mathrm{the} \mathrm{numbers}}{\mathrm{no} \mathrm{of} \mathrm{observations}}$

Given observations are 20, 70, 30, 25, 5

The number of observations = 5

Mean=$\frac{20+70+30+25+5}{5}=\frac{150}{5}=30$

Therefore, mean of the given numbers is 30.