An $$ideal$$ waveguide is given with a soft top $($p$(0)=0)$ and hard bottom $($dp$/$dz$($D$)=0)$

of depth D $=40$ m with a sound speed of $1500$ m$/$s and density of $1025$ kg$/$m$3.$ Assume no

absorption in the seawater. A CW source of unit strength of frequency $100$ Hz is at a depth of

$22\mathrm{.}8$ m$.$