1。In a stack of boards at a lumber yard, the 20th board counting from the top of the stack is immediately below the 16th board counting from the bottom of the stack. How many boards are in the stack? A.38 B.36 C.35 D.34 E.33 2. For a certain examination a score of 58 was 2 standard deviation below the mean,and a score of 98 was 3 standard deviations above the mean. What was the mean score for the examination? A.74 B.76 C.78 D.80 E.82 这两题都是没太看懂题意问的是什么,请NN们指点,帮忙解答一下,万分感谢! |