Question

The probability of a randomly selected adult in one country being infected with a certain virus is 0.005. In tests for the​ virus, blood samples from 22 people are combined. What is the probability that the combined sample tests positive for the​virus? Is it unlikely for such a combined sample to test​ positive? Note that the combined sample tests positive if at least one person has the virus.

The probability that the combined sample will test positive is? ____

​(Round to three decimal places as​ needed.)

Is it unlikely for such a combined sample to test​ positive?

A.It is unlikely for such a combined sample to test​ positive, because the probability that the combined sample will test positive is greater than 0.05.

B. It is not unlikely for such a combined sample to test​ positive, because the probability that the combined sample will test positive is greater than 0.05.

C.It is unlikely for such a combined sample to test​ positive, because the probability that the combined sample will test positive is less than or equal to than 0.05.

D.It is not unlikely for such a combined sample to test​ positive, because the probability that the combined sample will test positive is less than or equal to than 0.05.

Answer 1

Solution:-)

Let p be the probability of a randomly selected adult in one country being infected with a certain virus is 0.005.

We take blood samples from 22 people which are combined. The combined sample tests positive if at least one person has the virus. So, X~ Bin(22,0.005)

It isfairly  unlikely for such a combined sample to test​ positive, because the probability that the combined sample will test positive is smaller than 0.05