12) True or False: The exponential probability distribution has a negative skewed shape a. True b. False 13) A sample of 49 observations is taken from a normal population with a standard deviation of 10. The sample mean of 55. Determine the 95% Confidence Interval for the population mean. Use the z-value of 1.96 as your test statistic. a. 55 + or - 4.3 b. 55 + or - 2.2 c. 55 + or - 2.8 d. 55 + or - 1.8 14) To determine a confidence interval for the population mean with an unknown population standard deviation, we use the z statistic. a. True b. False