Question

A survey of 2301 adults in a certain large country aged 18 and older conducted by a reputable polling organization found that 406 have donated blood in the past two years.

construct and interpret 90% confidence interval for the population proportion of adults in the country who have donated blood in the past two years.

There is a 90% chance the proportion of adults in the country aged 18 and older who have donated blood in the past two years is between ? And ?

Answer 1

Values are given as,

n= 2301

x= 406

= (x/n) = (406/2301) = 0.1764

Z-critical value of 90% = 1.645

Calculating 90% confidence interval:

0.0079

CI= 0.1633 , 0.1895

The 90% confidence interval: (0.1633 , 0.1895)

Interpretation : There is a 90% chance the proportion of adults in the country aged 18 and older who have donated blood in the past two years is between 0.1633 and 0.1895 .