Answer
a) $L=\dfrac{k}{d^2}$
b) $ k=7000$dB/ft
c) $\dfrac{L}{4}$
d) $4L$
Work Step by Step
a) As per the given problem, we have:
$L=\dfrac{k}{d^2}$
Here, $k$ is defined as constant of proportionality
b) From part (a), we have $L=\dfrac{k}{d^2}$
Plug the given values in the above expression, we get
$70=\dfrac{k}{(10)^2}\implies k=7000$dB/ft
c) From part (a), we have $L=\dfrac{k}{d^2}$
Then, $L_n=\dfrac{k}{(2d)^2}=\dfrac{L}{4}$
d) From part (a), we have $L=\dfrac{k}{d^2}$
Then, $ L_n=\dfrac{k}{(d/2)^2}=4L$
