Problem $4.($An underwater source$)$ An underwater source of sound produces spherical waves in a freshwater lake. The intensity of the sound $5\mathrm{.}0$ m from the source is $7$ x $10-3$ W$/$m$^2$ A$.$ What is the intensity $2\mathrm{.}0$ m from the source? Use units of W$/$m$2$ B$.$ What is the total power of the source? Use units of W$.$ C$.$ Would either of your answers to parts A or B above change if the lake had saltwater in it instead of freshwater? a$.$ Both the answers to A and B would change b$.$ Only the answer to A would