First, lets know what the formula of mean is.
Mean = (Sum of individual values)/no of values
From the question:
Mean = 4.0
no of values = 5
To find x therefore;
[tex]\begin{gathered} \text{Mean = }\frac{1.2\text{ + 3.4 + 6.7 + 5.9 + x}}{5} \\ 4.0\text{ = }\frac{1.2\text{ + 3.4 + 6.7 + 5.9 + x}}{5} \\ 4.0\text{ = }\frac{17.2\text{ + x}}{5} \\ \text{Cross multiplying both equations, we will obtain} \\ 4.0\text{ }\times\text{ 5 = 17.2 + x} \\ 20\text{ = 17.2 + x} \\ \text{Collect like terms} \\ 20\text{ - 17.2 = x} \\ 2.8=\text{ x} \end{gathered}[/tex]Conclusion:
The value of x is 2.8.
