include null and alternate hypothesis, a p-value, and a conclusion PRIVATE about the null hypothesis
In a recent survey of gun control laws, a random sample of 1000 women showed that 650 were in favor of stricter gun laws. In a random sample of 1000 men, 600 favored stricter gun control laws. Determine a 90% confidence interval for the difference between the proportion of women and men who favor stricter gun laws.
Answer)
N1 = 1000, P1 = 650/1000
N2 = 1000, P2 = 600/1000
First we need to check the conditions of normality that is if n1p1 and n1*(1-p1) and n2*p2 and n2*(1-p2) all are greater than equal to 5 or not.
N1*p1 = 650
N1*(1-p1) = 350
N2*p2 = 600
N2*(1-p2) = 400
All the conditions are met so we can use standard normal z table to construct the interval.
Margin of error (MOE) = Z*Standard error
Critical value z from z table, for 90% confidence level is 1.645.
Standard error =√ [{(p1*(1-p1)}/n1 + {(p2*(1-p2)}/n2]
After substitution
MOE = 0.03556777597
Interval is given by
(P1-P2) - moe < (P1-P2) < (P1-P2) + MOE
0.01443222402 < (P1-P2) < 0.08556777597
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