The intensity of a sound wave while passing through an elastic medium falls down by 10% as it covers one meter distance through the medium. If the initial intensity of the sound wave was 100 db its value after it has passed through 3 meter thickness of the medium will be

Options

A. 60 decibel
B. 72.9 decibel
C. 81 decibel
D. 70 decibel.

Answer

B

Explanation

Here `I_(3) = (90)/(100) xx (90)/(100 xx (90)/(100) xx 100` dB
`I_(3) ` = 72.9 dB.
Correct choice is b.