You hear sounds at the following decibel levels: 5 dB, 10 dB, 20 dB, and 40 dB. Which sound is 10 times higher than the lowest pressure humans can hear?

40 dB

10 dB

20 dB

5 dB

The lowest pressure the human can hear is 20 micro Pa or 20x10^-6 Pa.

to convert it dB = 20 log (p / p0)

where p is the pressure you want to hear

p0 is the lowest pressure the human can hear

since you want 10 times higher the lowest possible

p/p0 = 10

dB = 20 log (10)

dB = 20 dB