posted by tristen .
11. A local health care company wants to estimate the mean weekly elder day care cost. A sample of 10 facilities shows a mean of $250 per week with a standard deviation of $25. What is the 90 percent confidence interval for the population mean?
Use a confidence interval formula:
CI90 = mean ± 1.645(sd/√n)
...where ± 1.645 represents the 90% confidence interval using a z-table, sd = standard deviation, √ = square root, and n = sample size.
Plug your data into the formula to calculate the confidence interval.
I hope this will help get you started.