Comments Standard Deviation
1. **State the problem:** We have 10 articles with comment counts: $\{15, 25, 10, 30, 20, 18, 22, 12, 28, 17\}$. We need to calculate the mean and standard deviation of these comments to understand audience engagement consistency.
2. **Calculate the mean (average):**
$$\text{mean} = \frac{15 + 25 + 10 + 30 + 20 + 18 + 22 + 12 + 28 + 17}{10} = \frac{197}{10} = 19.7$$
3. **Calculate each deviation from the mean and square it:**
$$\begin{aligned}
(15 - 19.7)^2 &= (-4.7)^2 = 22.09 \\
(25 - 19.7)^2 &= 5.3^2 = 28.09 \\
(10 - 19.7)^2 &= (-9.7)^2 = 94.09 \\
(30 - 19.7)^2 &= 10.3^2 = 106.09 \\
(20 - 19.7)^2 &= 0.3^2 = 0.09 \\
(18 - 19.7)^2 &= (-1.7)^2 = 2.89 \\
(22 - 19.7)^2 &= 2.3^2 = 5.29 \\
(12 - 19.7)^2 &= (-7.7)^2 = 59.29 \\
(28 - 19.7)^2 &= 8.3^2 = 68.89 \\
(17 - 19.7)^2 &= (-2.7)^2 = 7.29
\end{aligned}$$
4. **Sum the squared deviations:**
$$22.09 + 28.09 + 94.09 + 106.09 + 0.09 + 2.89 + 5.29 + 59.29 + 68.89 + 7.29 = 393.1$$
5. **Calculate the variance (sample variance, dividing by $n-1=9$):**
$$\text{variance} = \frac{393.1}{9} \approx 43.68$$
6. **Calculate the standard deviation:**
$$\text{standard deviation} = \sqrt{43.68} \approx 6.61$$
7. **Interpretation:**
The mean number of comments is about 19.7, with a standard deviation of 6.61. This indicates moderate variability in audience engagement across articles. Since the standard deviation is roughly one-third of the mean, engagement is somewhat inconsistent. The news site might want to investigate factors causing this variation to achieve more consistent engagement.
**Final answers:**
- Mean comments: $19.7$
- Standard deviation: $6.61$