Sound wave intensity of elephants

[sun]

Homework Statement

There is evidence that elephants communicate via infrasound, generating rumbling vocalizations as low as 14hz that can travel up to 10km. The intensity level of these sounds can reach 103dB, measured a distance of 5.0m from the source. Deteremine the intensity level of the infrasound 10km from the source, assuming the sound energy radiates uniformly in all directions.

Homework Equations

$$B$$=10log(I/10^-12)

The Attempt at a Solution

i found the intensity at an intensity level of 103dB to be.0199W/m^2. I'm just not sure where to go from here. Suggestions would be appreciated.

thanks

 

[rl.bhat]

Intensityi is inversly proportional to square of the distance.
Using I1/R1^2 = I2/R2^2, find I2. Then convert it into dB.