Recall that the average of a given set of numbers is the sum of the numbers divided by the number of numbers.
Therefore, if we want the average to be 82, and we call x the score on Test W, then:
[tex]82=\frac{81+75+88+x}{4}\text{.}[/tex]Multiplying by 4 we get:
[tex]\begin{gathered} 82\times4=244+x, \\ 328=244+x\text{.} \end{gathered}[/tex]Subtracting 244 from the equation we get:
[tex]\begin{gathered} 328-244=x, \\ x=84. \end{gathered}[/tex]Answer: The recruit must score at least 84 points on Test W.