Question

We're in class with a SIL decibel meter up front, and everyone is screaming at the top of their lungs, hooting and shouting and pounding on their desks, shooting off firecrackers, its Phys 1240 gone wild...and the meter is reading a reasonably steady sound intensity level of 120 dB. At a pre-arranged signal from Professor Parker, seventy-five (75) percent of the class suddenly gets totally quiet, while the remaining students continue making the same noise. What sound intensity level would the meter now show?