Textbook question. Need help in understanding how this is done. Not using for work other then to further understand the subject.
Suppose that Syd Water monitors water usage in a suburb and finds that for one summer the average household usage is 408 litres per day. A year later it examines records of a sample of 50 households and finds that there is a daily mean usage of 380 litres with a standard deviation of 25 litres.
- Construct a 95% confidence interval for the population
mean daily water usage in the second summer. Assume the
population usage is normally distributed.
- Interpret the interval constructed in (the question above).
- Do you think water usage has changed in the second