Answer
(a) $\Delta t=0.44s$ (b) $\lambda=0.028m$
Work Step by Step
(a) Since the waves travels toward the bottom of the ocean and back, the total distance equals $2(75m)=150m$. Using the fact that $$v=\frac{\Delta x}{\Delta t}$$ solve for $\Delta t$ to get $$\Delta t=\frac{\Delta x}{v}$$ Substituting known values of $\Delta x=150m$ and $v=343m/s$ yields a time of $$\Delta t=\frac{150m}{343m/s}=0.44s$$ (b) Use the fact that $$v=f\lambda$$ to solve for wavelength $\lambda$. $$\lambda=\frac{v}{f}$$ Substituting known values of $v=1530m/s$ and $f=55kHz=55000Hz$ yields a wavelength of $$\lambda=\frac{1530m/s}{55000Hz}=0.028m$$
