Question

...???.................... ...

Answer 1

$f = 2000hz \\ lambda = 0.35m \\ v = lambda \times f \\ v = 2000 \times 0.35 \\ v = 700m.s \\ \\ d = 1500m \\ t = \frac{d}{v} = \frac{1500}{700} = 2.14s$