This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Study the following table of population in a district and the average population served per doctor. Calculate the harmonic mean:\r\n \r\n\r\n\r\n\r\nAREA\r\n\r\n\r\nPOPULATION SERVED PER DOCTOR\r\n\r\n\r\nPOPULATION\r\n\r\n\r\nNUMBER OF DOCTORS\r\n\r\n\r\n\r\n\r\nRURAL\r\n\r\n\r\n1000\r\n\r\n\r\n50000\r\n\r\n\r\n50\r\n\r\n\r\n\r\n\r\nURBAN\r\n\r\n\r\n500\r\n\r\n\r\n50000\r\n\r\n\r\n100\r\n\r\n\r\n\r\n\r\nTOTAL\r\n\r\n \r\n\r\n100000\r\n\r\n\r\n150\r\n\r\n\r\n\r\n 
Select and explain. 
A. 500, B. 567, C. 667, D. 750
C: 667
Answer: C: 667 
Explanation: Calculation of harmonic mean is as follows: (50000+50000)/(50000/100+50000/50)=667 Ref : Medical biostatistics, 1st edition pg: 118