Question

The noise level in an empty examination hall is 43 dB. When 70 physics students are writing an exam, the sounds of heavy breathing and pens traveling rapidly over paper cause the noise level to rise to 59 dB (not counting the occasional groans). Assuming that each student contributes an equal amount of noise power, find the noise level when half of the students have left the examination hall. Do not enter the unit.

Answer 1