What is santa's average speed when visiting houses if he visits 800 million houses over 48 hours?

Well, "speed" normally = (total distance covered) / (time to cover the distance).

In this case, we don't know the total distance that Santa has traveled, so the question can be answered only if we're willing to consider some other meaning of "speed".

Maybe we could say that in this case, "speed" means the average rate at which he visits houses. Then ...

Speed of visits = (total houses visited) / (time to visit them).

Speed of visits = (800 million houses) / (48 hours)

Speed of visits = 16.67 million houses per hour.

That's 277.8 thousand houses per minute

That's 4,630 houses per second

it has to be b, about 97 percent.