
Answer:
expected area = 453.20 m^2
Step-by-step explanation:
The given data   11 ≤ r ≤ 13
[tex]\left \{ {{3/4(1-(12-r)^2} \atop {0}} \right.[/tex] Â Â Â Â o / w
Th expected area of the insulating circular region can be calculated using
= E([tex]\pi r^2 )[/tex]
= [tex]\pi E(r^2)[/tex]
we will have to calculate  [tex]E(r^2)[/tex]
attached is the remaining part of the solution