When rain falls on the land, it either seeps into the ground or becomes runoff, which flows downhill into rivers and lakes.
To solve this problem it is necessary to apply the concepts related to intensity as a function of power and area.
Intensity is defined to be the power per unit area carried by a wave. Power is the rate at which energy is transferred by the wave. In equation form, intensity I is

The area of a sphere is given by

So replacing we have to

Since the question tells us to find the proportion when

So considering the two intensities we have to


The ratio between the two intensities would be

The power does not change therefore it remains constant, which allows summarizing the expression to

Re-arrange to find 



Therefore the intensity at five times this distance from the source is 
When thermal energy of a substance increases, it's entropy(randomness) & Kinetic energy increases.
For more appropriate answer, you should put the options 'cause there could be more than one answer for this question.
If it takes

seconds to reach the car, then the distance

is

.
The bear's distance from the tourist's starting point is

For maximum

, we set the equations equal to each other:



so the distance is