Ms. Scarpaci complains that the street noise in her apartment is much louder than the noise in her upstairs neighbor’s apartment. To test her claim, you use a sound meter to check the noise in each apartment. Your meter registers 50 dB in Ms. Scarpaci’s apartment and only 30 dB in her neighbor’s. From these readings, how much louder is Ms. Scarpaci’s apartment than her neighbor’s?

 a. 20% louder

 b. 10 times louder

 c. 100 times louder

 d. not enough to be noticeable