Sally and Tim are using a closed air column to determine the speed of sound in the classroom. They hear a resonant length 51 cm from the top of the tube then another one when the water is 68 cm from the top of the tube by vibrating a 1024 Hz tuning fork over the column. What is the speed of sound in the classroom?
2. Explain how Mervin could tune a string to 512 Hz on his guitar using a 512 Hz tuning fork. 
3. Normal breathing has an intensity of 10 dB. The music at an average rock concert is 120 dB. How many times louder is the rock concert?
The Attempt at a Solution
I don't know the first two, but is number 3) 10^10 dB?
I need help on 1 and 2