Sound Level: the Intensity Level of a "Super-Silent" Power Lawn

Multiple Choice

Sound level: The intensity level of a "Super-Silent" power lawn mower at a distance of 1.0 m is 100 dB. You wake up one morning to find that four of your neighbors are all mowing their lawns using identical "Super-Silent" mowers. When they are each 20 m from your open bedroom window, what is the intensity level of the sound in your bedroom? You can neglect any absorption, reflection, or interference of the sound. The lowest detectable intensity is 1.0 × 10^-12 W/m².

A) 80 dB
B) 104 dB
C) 400 dB
D) 50 dB
E) 40 dB