Answer :
Solution :
[tex]$n_1=178, \hat p_1 = 0.48$[/tex]
[tex]$n_2=427, \hat p_2 = 0.38$[/tex]
[tex]$\hat p_1=\frac{x_1}{n_1}$[/tex]
[tex]$x_1=n_1 \hat p_1$[/tex]
= 178 x 0.48
= 85.44
≈ 85
[tex]$x_2=n_2 \hat p_2$[/tex]
= 427 x 0.38
= 162.26
≈ 162
a). Yes, the sample sizes are large enough to use the large sample confidence interval so as to estimate the difference in the population proportions.
Let [tex]$\hat p_1 = 0.48, \ \ \hat p_2 = 0.38, n_1 = 178 \ \ n_2 = 427$[/tex]
Where the [tex]$\text{subscript indicates}$[/tex] the age [tex]$18-29$[/tex] group and the 2 - subscript indicates the age [tex]$50-64$[/tex] group.
Since [tex]$n_1 \hat p_1 = 85.44$[/tex]
[tex]$n_1(1- \hat p_1)=92.56, \ \ n_2\hat p_2 = 162.26, \ n_2(1-\hat p_2) = 264.74 $[/tex]
are all at least 10, the sample sizes are large enough to use the large sample confidence interval.
[tex]$P_0=\frac{x_1+x_2}{n_1+n_2}$[/tex]
[tex]$=\frac{85.44+162.26}{178+427}$[/tex]
= 0.409421
[tex]$P_0 = 0.4074$[/tex]
[tex]$Q_0=1-P_0$[/tex]
= 1 - 0.4094
= 0.5906
b). 90% confidence interval is
[tex]$=\left( \hat p_1- \hat p_2 \pm \frac{z \alpha}{2} \times \sqrt{P_0Q_0\left(\frac{1}{n_1}+\frac{1}{n_2}}\right) \right)$[/tex]
[tex]$=\left( 0.48-0.38 \pm \frac{z \times 0.10}{2} \times \sqrt{0.4094 \times 0.5906\left(\frac{1}{178}+\frac{1}{427}}\right) \right)$[/tex]
[tex]$=(0.1 \pm z 0.05 \times 0.04387082)$[/tex]
[tex]$=(0.1 \pm 1.64 \times 0.0439)$[/tex]
[tex]$=(0.1 - 0.071996, 0.1+0.071996)$[/tex]
[tex]$=(0.028004, 0.171996)$[/tex]
[tex]$=(0.0280, 0.1720)$[/tex]
c). Zero is not included in the confidence interval. Answer is no. The difference in the two population proportion are different from each other.