This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Demography and Family Planning, Subject name: Social & Preventive Medicine
If a conraceptive has failure rate of 15, how many unplanned pregnancies will the female have in her reproductive period. 
Select and explain. 
A. 3.5, B. 4, C. 4.5, D. 5
C: 4.5
Answer: C: 4.5 
Explanation: Ans. is 'c' i.e., 4.5 Failure rate per HWY =Total accidental pregnancies--------------------------Total months of exposurex 1200"A woman's reproductive period is roughly from 15 to 45 years, i.e a period of 30 years"------ Park24th/e - 521* Thus,15 =Total accidental pregnancies--------------------------30 x 12x 1200Total accidental pregnancies = 4.5