Statistics- Confidence Interval

Question

In a Gallup poll, 1011 adults were asked if they consumed alcoholic beverages, and 64% of them said that they did. Construct a 90% confidence interval estimate of the proportion of adults who consume alcoholic beverages.

Please show all work including calculator steps.

Answer 1

Step 1:

The total number of adults who consumed alcoholic beverages are n :  1011.

The probability that adults who agreed is : 64 % = 0.64.

Definition of specific confidence interval for a proportion :  ,

where  is the population proportion.

is the sample proportion.

.

n is the sample size.

is the confidence interval.

Step 2:

for 90 % confidence interval is 1.65.

.

90% of confidence interval for the proportion is

90% of confidence interval for the proportion is .

Solution:

90% of confidence interval for the proportion is .