excercices:

Excercices:Q4.3.4: Page 111The same survey data base cited shows that 32 percent of U.S adults indicated that they have been tested for HIV at some points in their life .Consider a simple random sample of 15 adults selected at that time .Find the probability

that the number of adults who have been

tested for HIV in the sample would be:

Text Book : Basic Concepts and Methodology for the Health Sciences

1

Solution

n=15 , p= 0.32 ,q= 1-p=0.68

( ) ( ) , 0,1,2,....,X n Xn

f x P X x p q x nx

Text Book : Basic Concepts and Methodology for the Health Sciences

2

•(a )Three (Ans. 0.1457)

•(b ) Less than two ) . 0.02477(Ans

(c ) At most one ) . 0.02477Ans (

•(d )At least three (Ans. 0.9038)

(e ) ,between three and five inclusive.

Text Book : Basic Concepts and Methodology for the Health Sciences

3

Q4.3.5 • refer to Q4.3.4 , find the mean and the

variance?

•(Answer: mean = 4.8, • variance =3.264

•Standard deviation= 1.807• )

Text Book : Basic Concepts and Methodology for the Health Sciences

4