A smart phone manufacturer is interested in constructing a 95% confidence interval for the
proportion of smart phones that break before the warranty expires. 83 of the 1685 randomly
selected smart phones broke before the warranty expired. Round answers to 4 decimal places
where possible.
a. With 95% confidence the proportion of all smart phones that break before the warranty
expires is between ____
and _____
b. If many groups of 1685 randomly selected smart phones are selected, then a different
confidence interval would be produced for each group. About
percent of these ______
confidence intervals will contain the true population proportion of all smart phones that break
before the warranty expires and about ____
percent will not contain the true population
proportion.