Solve the Problem $z = x ^ { 2 } + y ^ { 2 }$

Multiple Choice

Solve the problem.
-Find the average height of the paraboloid $z = x ^ { 2 } + y ^ { 2 }$ above the annular region $36 \leq x ^ { 2 } + y ^ { 2 } \leq 49$ in the $x y - p l a n e$ .

A) 67
B) $\frac { 183 } { 2 }$
C) $\frac { 121 } { 2 }$
D) $\frac { 85 } { 2 }$