SOLUTION: In a sample of 100 Republicans, 72 favored the president’s anti - drug program; while in a sample of 150 Democrats, 84 favored his program. a. Is there a significant differenc

Question 1157182: In a sample of 100 Republicans, 72 favored the president’s anti - drug program; while in a sample of 150 Democrats, 84 favored his program.
a. Is there a significant difference in the proportions of the Democrats and the Republicans who favored the president’s anti-drug?
b. Estimate the difference at 95% confidence level.

Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
This is a two sample proportion test
z=(p hat r-p hat d)/ sqrt ( p1*(1-p1)/n1) + (p2(1-p2)/n2))
reject Ho if the 95% CI for the difference between the mean doesn't contain 0.
the difference between the means is 0.16
the SE is sqrt(.72*.28/100 + .56*.44/150)=0.0604
z is 1.96
half-interval is 0.1184, round to 0.12
the 95% CI for the difference between the two proportion means is (0.04, 0.28).
That is one answer. The meaning is that because zero is not in the interval, we are highly confident the true difference is not zero.
You can do this as a hypothesis test rejecting the null if |z|>1.96 for a two way test. It is.
On the calculator want STAT TESTS 9 2 Samp Z interval

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