Originally Posted by

**philipsach1** I'm sorry, these questions are posted elsewhere, but I can't really get any detailed answers.

7. Express the function y = 5^x as an equivalent function with base 3.

9. The decibel (dB) is used to measure the loudness of a sound. The equation D = 10 log I models the decibel level of a sound whose intensity is I watts per square metre (W/m^2). The decibel levels of a subway train and normal conversation are 115 dB and 60 dB, respectively. How many times as intense as normal conversation is the noise of a subway train?