A laboratory worker finds that 1.8% of his blood samples test positive for the HIV virus.If 270 blood samples are selected at random,is it appropriate to use a Normal model to approximate the distribution of the number that test positive for the HIV virus?
A)Yes; Normal model with μ = 4.86 and σ = 4.77 can be used to approximate the distribution.
B)No; Normal model cannot be used to approximate the distribution because nq

Question

A laboratory worker finds that 1.8% of his blood samples test positive for the HIV virus.If 270 blood samples are selected at random,is it appropriate to use a Normal model to approximate the distribution of the number that test positive for the HIV virus?
A)Yes; Normal model with μ = 4.86 and σ = 4.77 can be used to approximate the distribution.
B)No; Normal model cannot be used to approximate the distribution because nq < 10.
C)Yes; Normal model with μ = 4.86 and σ = 2.18 can be used to approximate the distribution.
D)No; Normal model cannot be used to approximate the distribution because np < 10.
E)Yes; Normal model with μ = 265.14 and σ = 2.18 can be used to approximate the distribution.

Quizplus · Accepted Answer

We need to check whether np and n(1-p) both are greater than 10 to use the Normal model.
Here, n= 270, p = 0.018, np = 4.86, and n(1-p) = 265.14, which means np < 10 and n(1-p) > 10.
Hence, we cannot use the Normal model to approximate the distribution. Option D is correct because np < 10.

A Laboratory Worker Finds That 1