6.2 The Standard Normal Distribution Table: Find Zc Critical Value A distribution of values is normal with a mean of 70 and a standard deviation of 8. Find the interval containing the middle-most 88% of scores. a.) The critical values Zc=Zc= (Round to 3 decimal places.) b.) The interval is (Round to 1 decimal place.) Enter your answer using interval notation. Example: (2.1,5.6)