Answer:
The 95% confidence interval for the proportion of residences that reduced their water consumption is (0.665, 0.835).
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.
In which
z is the zscore that has a pvalue of .
Sampled 100 residential water bills and found that 75 of the residences had reduced their water consumption over that of the previous year.
This means that
95% confidence level
So , z is the value of Z that has a pvalue of , so .
The lower limit of this interval is:
The upper limit of this interval is:
The 95% confidence interval for the proportion of residences that reduced their water consumption is (0.665, 0.835).