Question

Doctors have devised a test for leptospirosis that has the following property: For any person suffering from lepto, there is a 90% chance of the test returning positive. For a person not suffering from lepto, there is an 80% chance of the test returning negative. It is known that 10% of people who go for testing have lepto. If a person who gets tested gets a +ve result for lepto (as in, the test result says they have got lepto), what is the probability that they actually have lepto?

CAT 2021

A
7/10
CORRECT ANSWER WRONG ANSWER
B
8/11
CORRECT ANSWER WRONG ANSWER
C
1/3
CORRECT ANSWER WRONG ANSWER
D
1/2
CORRECT ANSWER WRONG ANSWER
Solution

Correct option is (C)

(C)