#### Answer

(a) The sound intensity at the position of the microphone is $1.1\times 10^{-3}~W/m^2$
(b) $1.1\times 10^{-7}~J$ of sound energy impinges on the microphone each second.

#### Work Step by Step

(a) $I = \frac{P}{A}$
$I = \frac{P}{4\pi~R^2}$
$I = \frac{35~W}{(4\pi)~(50~m)^2}$
$I = 1.1\times 10^{-3}~W/m^2$
The sound intensity at the position of the microphone is $1.1\times 10^{-3}~W/m^2$
(b) We can find the power received by the microphone.
$P = I~A$
$P = (1.1\times 10^{-3}~W/m^2)(1.0\times 10^{-4}~m^2)$
$P = 1.1\times 10^{-7}~W$
$P = 1.1\times 10^{-7}~J/s$
$1.1\times 10^{-7}~J$ of sound energy impinges on the microphone each second.