Answer
The correct answer is:
(f) $\frac{3L}{2}$
Work Step by Step
The wavelengths of the standing waves have this form:
$\lambda_n = \frac{2L}{n}$
All of the choices can be written in this form except for $\frac{3L}{2}$
The correct answer is:
(f) $\frac{3L}{2}$
