The intensity of sound I (as a multiple of the average minimum threshold of hearing intensity) is related to the decibel level D (or loudness of sound) according to

I = 10D/10

(a) Express 10D/10 using radical notation.

(b) The background noise level of a relatively quiet room has a decibel reading of 32. Find the intensity I1 of this noise level.

(c) A decibel reading of 140 is at the threshold of pain. If I2 is the intensity of this threshold and I1 is the intensity found in part (b), express the ratio I2/I1 as a power of 10. Then approximate this ratio?