A person standing 1.00 m from a portable speaker hears its sound at an intensity of 7.50  103 W/m2.

(a) Find the corresponding decibel level.
(b) Find the sound intensity at a distance of 35.0 m, assuming the sound propagates as a spherical wave.
(c) Find the decibel level at a distance of 35.0 m.

2 answers

a. db=10log(I/10^-12) I am not certain what your I is.
b. I=Iabove/35^2
c. db= 10 log (Iinb/10^-12)

as a note, on c, you should go down 3 db for each doubling of distance.
1>2 one doublin
2>4 two
4>8 three
8>16 four
16>32 five, so a at 35 meters, it ought to be down by 15+ db
98.8dB