Question

A laboratory worker finds that 3% of his blood samples test positive for the HIV virus. In a random sample of 70 blood tests, what is the standard deviation of the number of people that test positive for the HIV virus

Answer 1

Answer:

The standard deviation  of the number of people that test positive for the HIV virus =  

   σ  =1.427

Step-by-step explanation:

Explanation:-

Given the probability that test positive for the HIV virus 'p' = 3% =0.03

Given random samples 'n' = 70

by using binomial distribution

The mean of the samples test positive for the HIV virus  

                     μ = n p = 70 X 0.03 = 2.1

The standard deviation  of the number of people that test positive for the HIV virus

                σ =   $\sqrt{npq}$

                 σ  = √70 ×0.03×0.97 =√2.037 = 1.427

Conclusion:-

The standard deviation  of the number of people that test positive for the HIV virus =  σ      =1.427