The diagram is missing; however, we know that the intensity of a sound wave is inversely proportional to the square of the distance from the source:

where I is the intensity and r is the distance from the source.
We can assume for instance that the initial distance from the source is r=1 m, so that we put

The intensity at r=3 m will be

Therefore, the sound intensity has decreased by a factor

.
A closed space zone is one that is obstrutced in some way.
Hope this helps :)
Answer:
Explanation:
A
35 N Small Dog <=======BONE=========> Bigger Dog 42 N
B
Fnet = Large Dog - small dog The forces are subtracted because they are acting in opposite Directions.
Fnet = 42 - 35
Fnet = 7 N
C
m = 2.5 kg
F = 7 N
a = ?
F = m * a
7 = 2.5 a
a = 7 / 2.5
a = 2.8 m/s^2