Answer: The correct answer is "A dog runs an average of 8 mph".
Step-by-step explanation:
Speed is a scalar quantity. It has magnitude only. For example, a car is travelling with the speed of 60 km per second.
Velocity is a vector quantity. It has magnitude as well as direction. For example, a car is travelling with the speed of 60 km per second in the north direction.
Velocity is equal to the speed with direction.
In the given option, Cindy biked westward at 30 km/h. The velocity of the biked is given as both magnitude and direction are given.
A rock is to the left of a flowerpot. Only direction is given. It is neither speed nor velocity.
A dog runs an average of 8 mph. The speed of a dog is 8 mph as only the magnitude of the speed is given.
Leo lives 2 miles north of Andre. Only the direction is given.
Therefore, The correct answer is "A dog runs an average of 8 mph".