2. 职称英语
  3. From a set of 100 numbers, half were selected to form group I, and 60 percent of

From a set of 100 numbers, half were selected to form group I, and 60 percent of

游客2025-02-23  29
问题 From a set of 100 numbers, half were selected to form group I, and 60 percent of the remaining numbers were selected to form group II. The average (arithmetic mean) of the numbers ingroup I is 24.4, and the average of the numbers in group II is 31.5. Which of the following is closestto the average of the numbers in groups I and II combined?
选项 A、27.1
B、27.6
C、27.8
D、28.0
E、28.3
答案 A
解析 确定I中个数为100/2=50，确定Ⅱ中个数为(100-50)×60％=30，则平均值：(24-4×50+31.5×30)/(50+30)=27.0625，与A选项最接近。
转载请注明原文地址:https://tihaiku.com/zcyy/3969898.html
相关试题推荐
随机试题
最新回复(0)