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

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

σ =1.427

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 =
`√(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