A random sample of n measurements was selected from a population with unknown mean u and standard deviation o = 30 for each of the situations in parts a through d. Calculate a 90% confidence interval for u for each of these situations. a. n = 75, x = 25 b. n = 250, x = 110 c. n = 110, x = 13 d. n= 110, x =5.56 a. (Round to two decimal places as needed.) b. m (Round to two decimal places as needed.) c. (Round to two decimal places as needed.) (Round to two decimal places as needed.) e. Since we are given o = 30 we should use the standard normal distribution to get the critical value here. TRUE or FALSE? True O False