Another sound wave prob?

Question

A sound wave radiates from a source in all directions. If the power of the osund source is 200 watts, then the intensity level of the sound wave 100 m from the source is, in dB??

please help, thanks!!

Answer 1

just use the following
I = P / (4 Pi x^2)
= 200W / (4 Pi (100^2 m^2)
= crunch it (W/m^2)

then use
B = (10 dB) log ( I / I0)
where,
I0 = 10^-12 W / m^2

Answer 2

I just want to get to level 2