The # 1 always throws Me off

Question

The intensity of a sound varies inversely with the square of its distance from the source. At a distance of 1 meter,  the intensity of a jet engine noise is 10 watts per square meter. An airport cargo worker is 15 meters from the jet engine. What is the sound intensity at this distance? Round to the nearest thousandth 

Answer 1

Formula in words: The intensity of a sound varies inversely with the square of its distance from the source. 

 

Formula: I = k/d²

 

When d = 1, therefore I = k  and since I = 10 (watts/sq m) in this case, therefore k = 10.

 

Now when d = 15, I = k/d² is = 10/15²; theanswer is 10/225 watts/sq m in this case.  You can put it into decimal...