Explanation

Given numbers:
0.1, 0.21, 0.31, 0.41, 0.51

Step 1: Add all the numbers

$$0.1 + 0.21 + 0.31 + 0.41 + 0.51 = 1.54$$

Step 2: Divide by the number of values

$$frac{1.54}{5} = 0.308$$