Answer:
The variable of interest is the proportion of flips that land the correct way when flipped randomly.
The necessary conditions
and
are present.
The 98% confidence interval for the overall proportion of bottles that land correctly when flipped randomly is (0.131, 0.167).
Step-by-step explanation:
Variable of Interest:
Proportion of flips that land the correct way when flipped randomly.
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.
![\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}](https://tex.z-dn.net/?f=%5Cpi%20%5Cpm%20z%5Csqrt%7B%5Cfrac%7B%5Cpi%281-%5Cpi%29%7D%7Bn%7D%7D)
In which
z is the zscore that has a pvalue of
.
Necessary conditions:
The necessary conditions are:
![n\pi \geq 10](https://tex.z-dn.net/?f=n%5Cpi%20%5Cgeq%2010)
![n(1-\pi) \geq 10](https://tex.z-dn.net/?f=n%281-%5Cpi%29%20%5Cgeq%2010)
You observe 2180 random, independent flips, and 325 land the correct way.
This means that ![n = 2180, \pi = \frac{325}{2180} = 0.149](https://tex.z-dn.net/?f=n%20%3D%202180%2C%20%5Cpi%20%3D%20%5Cfrac%7B325%7D%7B2180%7D%20%3D%200.149)
Necessary conditions
![n\pi = 2180*0.149 = 325 \geq 10](https://tex.z-dn.net/?f=n%5Cpi%20%3D%202180%2A0.149%20%3D%20325%20%5Cgeq%2010)
![n(1-\pi) = 2180*0.851 = 1855 \geq 10](https://tex.z-dn.net/?f=n%281-%5Cpi%29%20%3D%202180%2A0.851%20%3D%201855%20%5Cgeq%2010)
The necessary conditions
and
are present.
98% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
The lower limit of this interval is:
![\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.149 - 2.33\sqrt{\frac{0.149*0.851}{2180}} = 0.131](https://tex.z-dn.net/?f=%5Cpi%20-%20z%5Csqrt%7B%5Cfrac%7B%5Cpi%281-%5Cpi%29%7D%7Bn%7D%7D%20%3D%200.149%20-%202.33%5Csqrt%7B%5Cfrac%7B0.149%2A0.851%7D%7B2180%7D%7D%20%3D%200.131)
The upper limit of this interval is:
![\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.149 + 2.33\sqrt{\frac{0.149*0.851}{2180}} = 0.167](https://tex.z-dn.net/?f=%5Cpi%20%2B%20z%5Csqrt%7B%5Cfrac%7B%5Cpi%281-%5Cpi%29%7D%7Bn%7D%7D%20%3D%200.149%20%2B%202.33%5Csqrt%7B%5Cfrac%7B0.149%2A0.851%7D%7B2180%7D%7D%20%3D%200.167)
The 98% confidence interval for the overall proportion of bottles that land correctly when flipped randomly is (0.131, 0.167).