Answer:

Explanation:
From the question, using the expression:

where;



This is a combined intensity of 4 speakers.
Thus, the intensity of 3 speakers = 
= 2.372 W/m²
Thus;


It's a quantitative observation because it includes numerical data.
Answer:
B. A repulsive force of 8.0*10^3 N.
Explanation:
As we know by Coulomb's law that the electrostatic force between two charges is given as

here we know that


r = 3.0 m
now we have


since both charges are similar charges so they will repel each other by the force we calculated above so correct answer will be
B. A repulsive force of 8.0*10^3 N.
work done = force * distance moved (in direction of the force)
force= mass* acceleration
force=58.1N
58.1*(5.8*10^4)
=3,369,800 J