1) The batteries used in a digital watch have an operating life that is normally distributed. As sample of 18 batteries reveals a mean of 2.35 years and a standard deviation of 0.4 years.
Find a 98% confidence interval for the population mean.
2) Find a 99% confidence interval for the population mean for the QUESTION 13.
3) A sample of 65 observations is taken from a normal population. The sample mean is 30, and the sample standard deviation is 4. Determine the 90 percent confidence interval for the populationmean. What are the UPPER bound and LOWER bound of the confidential interval?