This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Screening, Subject name: Social & Preventive Medicine
ELISA test has sensitivity of 95% and specificity of 95%. Prevalence of HIV carries is 5%. The predictive value of positive test is- 
Select and explain. 
A. 95%, B. 50%, C. 100%, D. 75%
B: 50%
Answer: B: 50% 
Explanation: Ref:Parks 23rd edition pg 139 Construct a 2x2 table using the above data. 4.75 4.75 0.25 9.25 PPV = TP / (TP + FP) = 4.75/(4.75+4.75)=0.5