Solve
-Find an Equation of the Form $y = a x ^ { 2 }$

Solve.
-Find an equation of the form $y = a x ^ { 2 }$ that describes the outline of a satellite dish such that the bottom of the dish passes through $( 0,0 )$ , the diameter of the dish is 20 inches, and the depth of the dish is 7 inches

A) $y = \frac { 7 } { 400 } x ^ { 2 }$
B) $y = \frac { 7 } { 20 } x ^ { 2 }$
C) $y = \frac { 7 } { 100 } x ^ { 2 }$
D) $y = \frac { 7 } { 10 } x ^ { 2 }$