1. A sample of 225 elements from a population with a standard deviation of 75 is selected. The sample mean is 180. Find the 95% confidence interval for u. 2. It is known that the variance of a population equals 1,936. A random sample of 121 has been taken from the population. There is a .95 probability that the sample mean will provide a margin of error of....? 3. A random sample of 144 observations has a mean of 20, a median of 21, and a mode of 22. The population standard deviation is known to equal 4.8. The 95.44% confidence interval for the population mean is... 4. A random sample of 49 statistics examinations was taken. The average score, in the sample, was 84 with a variance of 12.25. The 95% confidence interval for the average examination score of the population of the examinations is The Highway Safety Department wants to study the driving habits of individuals. A sample of 121 cars traveling on the highway revealed an average speed of 60 miles per hour with a standard deviation of 11 miles per hour. Determine a 95% confidence interval estimate for the speed of all cars. 6. In order to estimate the average time spent on the computer terminals per student at a local university, data were collected for a sample of $1 business students over a one-week period. Assume the population standard deviation is 1.8 hours. a. The standard error of the mean is b. With a 0.95 probability, the margin of error is approximately c. If the sample mean is 9 hours, then the 95% confidence interval is 7. A sample of 73 information system managers had an average hourly income of $40.75 with a standard deviation of $7.00. If we want to determine a 95% confidence interval for the average hourly income, The value of "t" statistics is b. The standard error of the mean is c. The value of the margin of error at 95% confidence is d. The 95% confidence interval for the average hourly wage of all information system managers is