A person standing $1\mathrm{.}15$ m from a portable speaker hears its sound at an intensity of $7\mathrm{.}90103$ W$/$m$2.$

HINT

$($a$)$

Find the corresponding decibel level.

$98\mathrm{.}98$ Don't confuse intensity with intensity level. Intensity is a physical quantity with units of watts per meter squared. Intensity level, or decibel level, is based on the logarithm of a ratio of intensities and gives an approximate measure of our perception of loudness. dB

$($b$)$

Find the sound intensity $($in W$/$m$2)$ at a distance of $30\mathrm{.}0$ m$,$ assuming the sound propagates as a spherical wave.

$0\mathrm{.}0000116$ W$/$m$2$

$($c$)$

Find the decibel level at a distance of $30\mathrm{.}0$ m$.$