If \(y \propto \frac{1}{x^2}\) and x = 3 when y = 4, find y when x = 2.
A
1
B
3
C
9
D
18
E
21
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
\(y \propto \frac{1}{x^2}\)
\(y = \frac{k}{x^2}\)
\(4 = \frac{k}{3^2}\)
\(k = 4 \times 3^2 = 36\)
\(y = \frac{36}{x^2}\)
When x = 2,
\(y = \frac{36}{2^2} = 9\)
Source: Myschool Past Questions Archive (Record #23709)