The city of Alameda is surveying residents to learn the proportion of smartphone users. They know that only
smartphones use data. They sampled active cell phone plans from five service providers to determine the proportion
that include data in the plan. Below are the results. What is the approximate confidence interval at 95% confidence level
for population proportion of smartphones to cell phones?
All cell phones Smartphones
(thousands) (thousands)
100
120
54
|
67
65
The survey indicates that 85% to 93% of cell phone plans include data for a smartphone.
The survey shows that 88% to 93% of subscribers to a cell phone plan own a smartphone.
The survey shows that 86% to 92% of cell phone plans include data for a smartphone.
The survey shows that 91% to 94% of subscribers to a cell phone plan own a smartphone.