Answer: A proton is a positively charged particle located in the nucleus of an atom.
The sound wave would behave differently in a swimming pool than in his bedroom because sound waves travel faster in more dense mediums; such as water. The wave will travel faster in water, and slower in air.
First convert the speed of sound from meters/second to miles/second:

Then the time it takes for the sound to travel 20 miles is

The answer to your question is -4