Calculate the mean deviation of the first five ... - JAMB Mathematics 2023 Question

The mean deviation (or average deviation) of a set of values from their mean is calculated using the formula:

$$\text{Mean Deviation}=\frac{\sum _{i=1}^n|X_i-\overline{X}|}{n},$$

where $X_i$ is each individual value, $\overline{X}$ is the mean of the values, and $n$ is the number of values.

The first five prime numbers are 2, 3, 5, 7, and 11. Let's calculate the mean deviation:

$$\overline{X}=\frac{2+3+5+7+11}{5}=\frac{28}{5}=5.6.$$

Now, calculate the mean deviation:

$$\text{Mean Deviation}=\frac{|2-5.6|+|3-5.6|+|5-5.6|+|7-5.6|+|11-5.6|}{5}$$

$$=\frac{3.6+2.6+0.6+1.4+5.4}{5}=\frac{13.2}{5}=2.64.$$

Therefore, the correct answer is approximately 2.72