Question

A June 2012 newspaper article stated that more than half of all American adults aged 18 years and older have very little or no confidence in Congress. This is based on a June 2012 Gallup poll in which 52% of a random sample of 997 American adults aged 18 years and older indicated little or no confidence in Congress.

The zz statistic for testing H0:p=0.5H0:p=0.5, where p is the proportion of all American adults aged 18 years and older who have very little or no confidence in Congress, based on the Gallup poll result is (±±0.0001):

z=z=

Answer 1

Test statistics

z = ( - p) / sqrt [ p (1 - p) / n ]

= ( 0.52 - 0.50) / sqrt ( 0.50 * 0.50 / 997 )

= 1.2630