Answer
* **Process B** has a **lower standard deviation** (1.55 mm) than **Process A** (1.89 mm).
* This means **Process B is more consistent** in terms of manufacturing error.
* Even though both processes have errors centered around zero (as seen in the mean), the **spread of errors** is smaller for Process B.
In manufacturing terms: **Process B is more reliable**.
Work Step by Step
Process A
$$
\bar{X}_A = \frac{0 + 1 + (-2) + 0 + (-2) + (-2) + 3}{7} = \frac{-2}{7} \approx -0.29
$$
$$
s^2_A = \frac{21.43}{7 - 1} = \frac{21.43}{6} \approx 3.57
$$
$$
s_A = \sqrt{3.57} \approx 1.89
$$
---
Process B
$$
\bar{X}_B = \frac{1 + (-2) + (-1) + 1 + (-1) + 2}{6} = \frac{0}{6} = 0
$$
$$
s^2_B = \frac{12}{6 - 1} = \frac{12}{5} = 2.40
$$
$$
s_B = \sqrt{2.40} \approx 1.55
$$
