Question

The focal length of a thin lens obtained by repeating measurements is given as follows: 10.1, 10.3, 9.9, 10.0, 9.8cm. what is the average focal length and the mean deviation.

Answer 1

Average:

$$a=\frac{10.1+10.3+9.9+10+9.8}{5}=10\text{ cm}.$$

Mean deviation:

$$m=\frac{(10.1-a)+(10.3-a)+(a-9.9)+(10-a)+(a-9.8)}{5}=0.14\text{ cm}.$$