1. The problem statement, all variables and given/known data How much acoustic power propagates through a spherical surface (sound source in centre) with radius equal to 1.0m? with radius equal to 5.0m? I = 10^-2 W/m^2 r = 1.0m or 5.0m f = 50kHz t = 2.0*10^-3s IL = 100dB 2. Relevant equations I = P/4∏r^2 3. The attempt at a solution i figured out that when r = 1.0, power must be 1.3*10^-1W. However, when I work out the intensity when r = 5.0, i get: 10^-2 = P/4*∏*25 (10^-2)(4*∏*25) = P 3.1W = P However, the answer states that the power for both spheres is 0.12W... What concept am I not understanding?