In order to calculate the expected value of x, we can divide the total number of desks by the total number of classrooms, so we have:
[tex]\begin{gathered} E(x)=\frac{11\cdot3+14\cdot1+40\cdot2+41\cdot3+42\cdot1}{10} \\ E(x)=\frac{292}{10} \\ E(x)=29.2 \end{gathered}[/tex]So the expected value of x is 29.2.