Answer:
6.28 or 157/25
Step-by-step explanation:
Firstly, you find the formula for the circumference of a circle which is C= PI ( diameter)
So since the radius is 1 you multiply it by 2 and get 2 so then you multiply 2 by 3.14 (pi) and get 6.28
I hope this helped!!!

Billion gallons per day, because the independent quantity is volume of water in billion gallons and dependent quantity is time in days.
Answer:
Step-by-step explanation: