Answer:
The upper bound of a 99% confidence interval for the percentage satisfied for all customers in the database is 88.70%.
Step-by-step explanation:
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
.
Sample of 252 customers, 208 are satisfied:
This means that ![n = 252, \pi = \frac{208}{252} = 0.8254](https://tex.z-dn.net/?f=n%20%3D%20252%2C%20%5Cpi%20%3D%20%5Cfrac%7B208%7D%7B252%7D%20%3D%200.8254)
99% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
The upper limit of this interval is:
![\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.8254 + 2.575\sqrt{\frac{0.8254*0.1746}{252}} = 0.8870](https://tex.z-dn.net/?f=%5Cpi%20%2B%20z%5Csqrt%7B%5Cfrac%7B%5Cpi%281-%5Cpi%29%7D%7Bn%7D%7D%20%3D%200.8254%20%2B%202.575%5Csqrt%7B%5Cfrac%7B0.8254%2A0.1746%7D%7B252%7D%7D%20%3D%200.8870)
As a percentage:
100%*0.8870 = 88.70%
The upper bound of a 99% confidence interval for the percentage satisfied for all customers in the database is 88.70%.
Answer:
X=1/3
Y= -1/2
Step-by-step explanation:
I don't remember how to do this but all I could think of is to find the value of x and y. I hope this is somewhat helpful.
Answer:
£54 and 168.75 mins
Step-by-step explanation: