You hear a fire truck with a certain intensity, and you are about 1 mile away. another person hears the same fire truck with an intensity that is about 10 times less. roughly, how far is the other person from the fire truck in miles?

The intensity of sound is just like the force of gravity, the force between electric charges, and the intensity of light . . . they all DEcrease at the same rate that the SQUARE of the distance INcreases.

So if two people are watching or listening to the same source, and one intensity is 1/10 as intense as the other intensity, then the farther person must be  √10  times as far from the source as the nearer person is.

√10 = 3.1622 ...

So the second guy is about 3.16 miles from the fire truck.  

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27