Question

An article summarized results from a national survey of 2302 Americans age 8 to 18. The sample was selected in a way that was expected to result in a sample representative of Americans in this age group.

(a) Of those surveyed, 1223 reported owning a cell phone. Use this information to construct a 90% confidence interval estimate of the proportion of all Americans age 8 to 18 who own a cell phone. (Round your answers to three decimal places.)

(b) Of those surveyed, 1529 reported owning an MP3 music player. Use this information to construct a 90% confidence interval estimate of the proportion of all Americans age 8 to 18 who own an MP3 music player. (Round your answers to three decimal places.)

Answer 1

a)

0.5313   1.64 0.5313 ( 1 - 0.5313 ) / 2302

0.5313   0.0171

0.514 , 0.548

At 90 % CI for proportion is ( 0.514 , 0.548 )

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b)

0.6642   1.64 0.6642 ( 1 - 0.6642 ) / 2302

0.6642   0.0161

0.648 , 0.680

At 90 % CI for proportion is ( 0.648 , 0.680 )