im reading the text of dave benson about music and maths and i have 2 questions from the text which i need an answer to. 1. power intensity is proportional to the square of the amplitude. how many decibles represent a doubling of the amplitude of a signal? (my answer is 4 but im not sure). 2. (multiple choices) two independents 70 dB sound sources are heard together. how loud is the resultant sound to the nearest dB? a. 140 dB b. 76 dB c. 73 dB d. 70 dB e. none of above now im stuck at it because i think it is either a or d. thanks for any help.