Answer
See explanation.
Work Step by Step
a. The sound will be maximally reinforced when the path difference is an integer multiple of wavelengths.
$\lambda = 34 cm$.
Constructive interference occurs for $150cm-x=0, \lambda, 2\lambda, 3\lambda, 4\lambda, …$
The values of x are 150 cm, 116 cm, 82 cm, 48 cm, 14 cm.
b. The sound will be canceled when the path difference is an odd multiple of half wavelengths.
Destructive interference occurs for $150cm-x=\lambda/2, 3\lambda/2, 5\lambda/2, 7\lambda/2, …$
The values of x are 133 cm, 99 cm, 65 cm, 31 cm.
