A random sample of 78 eighth grade students' scores on a national mathematics assessment test has a mean score of 273. This test result prompts a state school administrator to declare that the mean score for the state's eighth graders on this exam is more than 270. Assume that the population standard deviation is 31. At a = 0.14, is there enough evidence to support the administrator's claim? Complete parts (a) through (e). A. Ho: 270 (claim) Ha: 270 (claim) (b) Find the standardized test statistic z. B. Ho270 (claim) Ha>270 E. Ho: 270 (claim) F. Ho: = 270 (claim) Ha: 270 (claim) : >270 z= (Round to two decimal places as needed.)