Determine the Constant of Variation for the Stated Condition $y$ Varies Directly as the Square Root Of

Multiple Choice

Determine the constant of variation for the stated condition.
-If $y$ varies directly as the square root of $x$ , and $y = 9$ when $x = 49$ , find $y$ when $x = 36$ .

A) $\frac { 54 } { 7 }$
B) $\frac { 324 } { 49 }$
C) $\frac { 21 } { 2 }$
D) $\frac { 49 } { 4 }$