1. The problem statement, all variables and given/known data When four quadruplets cry simultaneously, how many decibels greater is the sound intensity level than when a single one cries? 2. Relevant equations B=10*log(I/I_0) 3. The attempt at a solution I_0 is arbitrary (its just a reference). When 4 babies cry, I would assume that it is the equivalent of 4 sound sources. Thus the amplitude would be 4 times larger than a single sources (or single crying baby) Because intensity is proportional to amplitude square, I would assume I/I_o is 16..... Putting this into the formula: 10*log(16/1) is 12. The solutions say to do 10*log(4/1) which equals 6 implying that the intensity is only 4 times as great.