The empirical rule states that 65% of the data under the normal curve is within 1 standard deviation of the mean, 95% of the data is within 2 standard deviations of the mean, and 99% is within 3 standard deviations of the mean.
The approximation to the distribution of the sample proportion has the following shape:
[tex]\hat{p}\approx(p;\frac{p(1-p)}{n})[/tex]
The mean of the distribution is the sample proportion: μ= p
The standard deviation of the distribution is the square root of the variance
σ=√[p(1-p)/n]
For the given distribution:
μ= 0.14
σ= 0.02
95% of the distribution is μ ± 2σ
Upper bound:
[tex]\mu+2\sigma=0.14+2\cdot0.02=0.18[/tex]
Lower bound:
[tex]\mu-2\sigma=0.14-2\cdot0.02=0.10[/tex]
The 95% confidence interval is [0.10;0.18]
