Plis help 25 points

Can you guys plz answer this question in order and quickly plz i will give 30 points

It takes a total of 6 hours to fill up an inground backyard pool using a standard house. a function can represent this situation to represent the amount of water in the pool until it is full a function of time the hose is running. determine the domain for the function

What is the number 321,000,000 in scientific notation? also what is the number? ?