Question

The table above shows the result of a test that is designed to give a positive indicator when patients are infected with a certain virus and a negative indicator when they are not infected . According to the result, what is the probability that the test gives the incorrect indicator?

	Test negative	Test positive	Total
Has virus	30	370	400
Does not have virus	550	50	600
Total	580	420	1000

• A. 5%
• B. 8%
• C. 10%
• D. 13%

Answer 1

Answer: (B)

8%

From the given table,

Number of incorrect indicator $=30$ (When patients has virus)

Number of incorrect indicator $=50$ (When patients does not have virus)

Total number of incorrect indicator $A=80$

Number of total patients $B=1000$

Required probability $=\frac{A}{B}=\frac{80}{1000}=8$%

Hence, this is the answer.