Suppose a speaker is sending out a signal of a given power uniformly in all dire

Question

Suppose a speaker is sending out a signal of a given power uniformly in all directions. You are located a certain distance from the speaker measuring the intensity of the sound. Given the following different situations, rank the measured intensity (1 = the lowest intensity).
1 2 3 4 5  Power of speaker is P and distance to speaker is d.
1 2 3 4 5  Power of speaker is (1/9)P and distance to speaker is 3d.
1 2 3 4 5  Power of speaker is 2P and distance to speaker is 2d.
1 2 3 4 5  Power of speaker is (1/4)P and distance to speaker is (1/2)d.
1 2 3 4 5  Power of speaker is 4P and distance to speaker is 2d.

Explanation / Answer

given power, P
distance from the speaker = d
intensity of sound measured = P/4pid^2 = Io

case 1 : Io
Case 2 : I = Io/9*9 = Io/81
Case 3 : I = Io/2
Case 4 : I = Io
Case 5 : I = Io

so ranking is
case 1 : 5
case 2 : 1
case 3 : 4
case 4 : 1
case 5 : 1

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