Answer:
strange phrasing of a question
If one assumes that the "observation" was from 3:00 pm - 5:00 pm (2 hours) 
and the ball was ONLY "bounced" 10 times (3+7) 
we can can say that the rate was 10 bounces/2 hours or 5 b.p.h. (bounces per hour) 
Explanation: