Chapter 14 - Sound - Learning Path Questions and Exercises - Exercises - Page 524: 26

$1.6dB$

Intensity is inversely proportional to square of distance. So, $\frac{I_{1}}{I_{2}}=\frac{R_{2}^{2}}{R_{1}^{2}}$ Let required intensity be $I$ So, $\frac{I}{160}=\frac{100}{10000}=\frac{1}{100}$ The intensity level 100 m away is $1.6 dB$