Q.Find the mean deviation about the mean for the data: $10, 11, 7, 13, 12, 5, 9, 8, 14, 11$.

[!TLDR] Find $\bar x$, then average $|x_i-\bar x|$ over $n=10$. [!ANSWER] Mean $=10$, …

The data $10,11,7,13,12,5,9,8,14,11$ has $n=10$. Sum $=10+11+7+13+12+5+9+8+14+11=100$, so $\bar x=100/10=10$. Absolute deviations: $|10-10|=0$, $|11-10|=1$, $|7-10|=3$, $|13-10|=3$, $|12-10|=2$, $|5-10|=5$, $|9-10|=1$, $|8-10|=2$, $|14-10|=4$, $|11-10|=1$. Sum $=0+1+3+3+2+ …

Compute $\bar x=\frac1n\sum x_i$, form $|x_i-\bar x|$ for every observ …

Arithmetic slips while adding ten separate absolute-deviation terms are the most common source of error here; adding in the same left-to-right order as listed, and …