Question 1159164: A nationwide survey claimed that more than 55% of parents with young children condone spanking their child as a regular form of punishment. In a random sample of 130 parents with young children, 73 said that they condone spanking. Test the claim, using the Confidence Interval method and .
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! Ho: p=0.55
Ha: p ne 0.55
alpha=0.05 p{reject Ho|Ho true}
p hat is 73/130 =0.5615
95% CI is phat +/- z* SE, where z is 1.96 and SE is sqrt (phat*(1-phat)/n)
this is 1.96*0.0435=0.0853
95% interval is (0.4762, 0.6468) or (0.48, 0.65)
Since values 0.55 is in the interval fail to reject. One-sided confidence intervals are often not used in place of two sided, so I set this up as a two-sided test, given that confidence intervals were wanted.
If it were testing 1-way, then the critical value would be z>1.645
and the calculation would be .0115/0.0463 and the z value of 0.26 would also mean insufficient evidence to reject Ho.
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