The telephone company wants to estimate the proportion of
households that would purchase an additional telephone line if it
were made available at a substantially reduced installation
cost. A random sample of 500 households is selected.
The results indicate that 135 of the households would purchase that
additional telephone line at a reduced installation cost.
Set up a 99% confidence interval estimate of the population
proportion of households that would purchase the additional
telephone line.
Provide responses to the following questions related to the
confidence interval estimate above:
What is the correct z-value for a 99% confidence
interval? Remember, if an exact value is not
available on the table but you can directly interpolate, provide
that value. Otherwise, use the closest
value. (Use the tabled values that you were
provided for use in class):
What is the standard deviation of the sampling proportion
(to four decimal places)?
Provide (to four decimal places) the confidence interval
estimate values:
≤ p ≤