In: Statistics and Probability
A poll taken before an election finds that 42 of 80 people asked favored the incumbent candidate. What is the 99% confidence interval for the proportion of voters that favor the incumbent?
Here to compute the Confidence Interval for population proportion we have to use z distribution i.e sampling Distribution for sample proportion as below,
The formula for 99% Confidence Interval for population proportion is given below,
The z critical value is calculated using Standerd normal z-table or using Excel.
The 99% Confidence Interval for population proportion is 38.1% & 66.9%.
Thank you.