Question

An underwater microphone is used to record sounds emitted by porpoises. The minimum intensity level the instrument can record is 10 dB. Assuming a porpoise emits sound at a rate of 0.05 J/s, what will be the max distance at which the animal will still be recorded? Neglect sound absorption in water, and treat the porpoise as a point sound source.

..i am very unsure of how to go about answering this question, any help would be great.