At The Amusement Park, Jill Rode A Roller Coaster That Went As Fast As 70 Mph. At The End Of The Ride, She Got Off Where She Started. What Is True About Her Average Speed And Average Velocity On The Roller Coaster?

We don't know her average speed, because insufficient information is provided. We can say it is less than 70 mph and greater than 0 mph.

Jill's average velocity is zero, because her net travel distance is zero.