Sample Size = n = 30
Number of smartphone users = x = 12
Proportion of smartphone users = p = x/n = 12/30 = 0.4
Confidence interval = 96%
Z-value for confidence interval = 2.054
Error term of the interval is given by:
[tex]E = z \sqrt{ \frac{p(1-p)}{n} } \\ \\
E=2.054 \sqrt{ \frac{0.4(0.6)}{30} } \\ \\
E=0.184
[/tex]
The 96% confidence interval will be p ± E .
p - E = 0.4 - 0.184 = 0.216
p + E = 0.4 + 0.184 = 0.584
Therefore, the 96% confidence interval will be (0.216, 0.584)
