Why do we use Z score to build on confidence intervals rather than t score?
You are getting ready to take a sample from a large population, and need to determine the appropriate sample size. You are estimating sales at a large chain of department stores. A previous survey from the same population found a standard deviation of $18. What sample size is ...
A random sample of size 81 is taken from a large population, measuring the time it takes to complete a drivers license examination. The sample mean was found to be 43 minutes, and the sample standard deviation 5.71 minutes. Construct a 95% confidence interval around the ...