This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: JIPMER 2018, Subject name: Physiology
When the HR is 72 beats per min, what would be the duration of cardiac cycle? 
Select and explain. 
A. 445 ms, B. 1450 ms, C. 700 ms, D. 833 ms
D: 833 ms
Answer: D: 833 ms 
Explanation: Cardiac cycle: - 72 beats occur in - 60sec. 1 beat would occur in - 60/72 1 beat - 0.833 sec (~ 833 ms) (0.0139 minute per beat).