Question

A person moving through a tuberculosis prone zone has a 50% probability of becoming infected. However, only 30% of infected people developed the disease. What percentage of people moving through a tuberculosis prone zone remains infected but does not show symptoms of disease?

• A. 15
• B. 33
• C. 35
• D. 37

Answer 1

The correct option is C 35

Method I:
It given that, 30% of the infected (50% of total) develop the disease while 70% of the infected do not develop, so the persons who gets infected but do no develop the disease are,

= 70% of 50% of total

$=\left(\frac{70}{100}\right)\times \left(\frac{50}{100}\right)$ × 100% = 35%

Method II:

So, % of people remains infected but not develop disease

= 50% × 70%

$=\frac{50}{100}\times \frac{70}{100}=\frac{35}{100}$ = 35%