标题: prep2题数学，找不到解释，求助！！ [打印本页] 作者: sswat88 时间: 2011-1-17 19:32 标题: prep2题数学，找不到解释，求助！！ A student worked for 20 days. For each of the amounts shown in the first row of the table, the second row gives the number of days that the student earned that amount. What is the median amount of money that the student earned per day for the 20 days? 对应图片1 (A) $96 (B) $84 (C) $80 (D) $70 (E) $48
A vending machine is designed to dispense 8 ounces of coffee into a cup. After a test that recorded the number of ounces of coffee in each of 1,000 cups dispensed by the vending machine, the 12 listed amounts, in ounces, were selected from the data. If the 1,000 recorded amounts have a mean of 8.1 ounces and a standard deviation of 0.3 ounce, how many of the 12 listed amounts are within 1.5 standard deviations of the mean? 对应图片2 (A) Four (B) Six (C) Nine (D) Ten (E) Eleven作者: hikiliu 时间: 2011-1-17 22:09
需要图片吗？作者: sakyamomo 时间: 2011-1-18 19:39
20天么 20天的中数就是第10天 11天赚的钱的平均数 根据图 第10天 11天都是84块 所以答案选84 你把中数跟平均数的概念好好看看就能搞定这类题了作者: sakyamomo 时间: 2011-1-18 19:42
第二题也是的 是1。5个标准方差 就是那个deviation 一个deviation是0.3 1.5个就是0.45