A random sample of 100 observations from a normally distributed population possesses a mean equal to 91.2 and a standard deviation equal to 9.7. Use this information to complete parts a through e below. a. Find a 90% confidence interval for mu. ( 89.60, 92.80) (Round to two decimal places as needed.) b. What do you mean when you say that a confidence coefficient is 0.90? A. A confidence coefficient of 0.90 means that 90% of the values in any sample taken from the population will be contained in an interval estimator constructed using this coefficient. B. A confidence coefficient of 0.90 means that there is a probability of 0.90 that an interval estimator constructed using this coefficient will enclose the population parameter. C. A confidence coefficient of 0.90 means that there is a probability of 0.90 that an interval estimator constructed using this coefficient will contain all of the values in the relevant sample. D. A confidence coefficient of 0.90 means that 90% of the values in the population will be contained in an interval estimator constructed using this coefficient.