Respuesta :

MathPhys

Answer:

5.42 meters

Explanation:

Sound intensity varies inversely with the square of distance:

I = k / r²

When r = 5, I = 100.

100 = k / 5²

k = 2500

I = 2500 / r²

When I = 85:

85 = 2500 / r²

r = 5.42