Chapter 6, Section 1-CI, Exercise 024

Social Networking Sites

In a survey of 2255

randomly selected US adults (age 18

or older), 1787

of them use the Internet regularly. Of the Internet users, 1054

use a social networking site.¹ Find a 90%

confidence interval for each of the following proportions.

¹Hampton, K., Goulet, L., Rainie, L., and Purcell, K., ''Social Networking Sites and Our Lives," Pew Research Center, June 16, 2011.

(a) Proportion of US adults who use the Internet regularly.

Round your answers to three decimal places.

The 90%

confidence interval is

to

.

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(b) Proportion of US adult Internet users who use a social networking site.

Round your answers to three decimal places.

The 90%

confidence interval is

to

.

Show Hint

Link to Text

(c) Proportion of all US adults who use a social networking site.

Round your answers to three decimal places.

The 90%

confidence interval is

to

.

Use the confidence interval to estimate whether it is plausible to estimate that 50%

of all US adults now use a social networking site.