Answer: There is no way of finding out if the clock worked before then, and if it stopped at P.m or A.m.
Step-by-step explanation:
Let's say the robber broke the clock at 3 a.m, the police would first of all not have any idea if the clock was indeed broken before the robber knocked it over, and the clock has no way of saying whether it was broken at 3 a.m. or 3 p.m, therefore it's rendered useless.
