The equation I = P av /4r 2 is predicated on the assumption that the transmitting medium

Question:

The equation I = P_av/4πr² is predicated on the assumption that the transmitting medium does not absorb any energy. It is known that absorption of sound by dry air results in a decrease of intensity of approximately 8 dB/km. The intensity of sound at a distance of 120 m from a jet engine is 130 dB. Find the intensity at 2.4 km from the jet engine

(a) Assuming no absorption of sound by air, and

(b) Assuming a diminution of 8 dB/km. (Assume that the sound radiates uniformly in all directions)