9 NO A random sample of n = 16 is drawn from a normally distributed population with a known standard deviation of o = 3.2. The sample mean is = 38.5 What is the 99.5% confidence interval for the population mean? O a. (36.25, 40.75) O b.(37.62, 39.38) O c. (36.74, 40.26) Od. (37.13, 39.87)

A sample of n = 18 data values randomly selected from a normally distributed population has variance s = 24.8. Construct a 95% confidence interval for the population variance. Round your endpoints to one decimal place. < o? <

The random sample shown below was selected from a normal distribution. 7, 10, 8, 3, 6, 2 O Complete parts a and b. ..... a. Construct a 90% confidence interval for the population mean p. ( 3.51 , 8.49 ) (Round to two decimal places as needed.) b. Assume that sample mean x and sample standard deviation s remain exactly the same as those you just calculated but that are based on a sample of n= 25 observations. Repeat part a. What is the effect of increasing the sample size on the width of the confidence intervals? The confidence interval is ( ). (Round to two decimal places as needed.)

The z confidence interval for the mean of a Normal population will have a specified margin of error m when the sample size is: a. n = (=*o/m). b. n = (z/m)². O c. n = (*o/m)². d. n ==*o/m.