To calculate the deviation of a data point from the mean, you subtract the mean from the data point. Here, we have:
- Mean = 9
- Data point = 8
The deviation can be calculated as follows:
\[ \text{Deviation} = \text{Data point} - \text{Mean} = 8 - 9 = -1 \]
So, the deviation of the data point 8 from the mean 9 is -1. This indicates that the data point is 1 unit below the mean.