Hello! I am doing some questions about sound waves for my homework assignment and have some problem in one of them. Assuming that it radiates sound uniformly, find the sound power from a motor car whose sound level at a distance of 7.5m is 87dB. Here are my steps: I = sound intensity, I_0 = minimum audible intensity By h = 10log(I/I_0) 87 = 10 log (I / 10x10^-12) I = 5.01 x 10^-4 W/m^2 By I = P / 4 pi r^2 5.01x 10^-4 = P / 4 pi 7.5^2 P = 0.354W But the answer given by my teacher is 0.18W...Can anyone tell me what's wrong in my calculation. Thanks!