Suppose you have 67 samples with sample standard deviation 2.5. A 99% confidence interval for the population mean is ?¯±x¯±d. What is d?

A sample of 1100 observations taken from a population produced a sample proportion of 0.36 . Make a 90 % confidence interval for p . Round your answers to three decimal places.

Arsenic is a compound that occurs naturally in very low concentrations. Arsenic blood concentrations in healthy individuals are Normally distributed with a mean of 3.2 mg/dl. Some areas of the United States have naturally elevated arsenic levels in the ground and water supplies. Researchers took a sample 20 water samples from a particular area and measured the arsenic levels in each of the 20 water samples. They want to determine if there is sufficient evidence to conclude that the arsenic level in that area is higher than 3.2 mg/dl. hypothesis test for one population mean (unknown population standard deviation) confidence interval estimate for one population mean (unknown population standard deviation) hypothesis test for population mean from paired differences confidence interval estimate for population mean from paired differences hypothesis test for difference in population means from two independent samples confidence interval estimate for difference in population means from two…

A population has a mean μ=88 and a standard deviation σ=28. Find the mean and standard deviation of a sampling distribution of sample means with sample size n=49.   μx= (Simplify your​ answer.) ​