Question 1168109: 2. Suppose a presidential candidate wants to compare the preferences of registered voters
in the northeastern United States with those in the southeastern United States. Such
a comparison would help determine where to concentrate campaign efforts. The candidate hires a professional pollster to randomly choose 1,500 registered voters in the northeast and 2,000 in the southeast and interview each to learn of her or his voting preference.
Construct a 95% confidence interval for the difference between population proportion of voters in Northeast and the population proportion of voters in Southeast.
Results of Poll
Northeast Southeast
n1 = 1,500 n2 = 2,000
x1 = 546 x2 = 475
Please helps thanks!
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! p1=0.364
p2=0.2375
the difference is 0.1265
the SE is sqrt (0.364*0.636/1500)+(0.2375*0.7625/2000). this is sqrt (p1*(1-p1)/n2+p2(1-p2)/n2))
=0.0156
the CI half-interval is 1.96*0.0156=0.0306
this is added to and subtracted from the mean to get (0.0959, 0.1571)
Where you round and how much determines that last two decimal places.
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