一道数学题

stellachan

  

7.51      8.22         7.86           8.36

8.09      7.83         8.30           8.01

7.73      8.25        7.96            8.53

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,howmany of the 12 listed amounts are written 1.5 standard deviations of the mean?

答案是11

请问题目中的问题是什么意思???

[此贴子已经被作者于2009-5-31 0:34:57编辑过]

bighaha

看不见图无法详尽解答。

题干意思：12个元素的数列，告诉平均值，标准差。求元素偏移量满足条件的个数？

[此贴子已经被作者于2009-5-31 0:14:39编辑过]

stellachan

再请问下 要满足的条件是什么???就是标准差变成1.5是吗??

xp635

1.5 standard deviation =1.5*0.3=0.45

mean=8.1, range under 1.5 standard deviation(7.65, 8.55)

just one number is out of this range, 7.51

so, answer is 11, Am I understood?

bighaha

以下是引用xp635在2009-5-31 0:51:00的发言：

1.5 standard deviation =1.5*0.3=0.45

mean=8.1, range under 1.5 standard deviation(7.65, 8.55)

just one number is out of this range, 7.51

so, answer is 11, Am I understood?

YUP, NICE MOVE.

stellachan

以下是引用xp635在2009-5-31 0:51:00的发言：

1.5 standard deviation =1.5*0.3=0.45

mean=8.1, range under 1.5 standard deviation(7.65, 8.55)

just one number is out of this range, 7.51

so, answer is 11, Am I understood?

如果是这样的话 就是1.5倍的standard deviation喽??

明白了

总是看不懂题目

syxphoebe

来学习喽~ 一样是读题啊

多谢stellachanMM 多谢各位朋友的解答 O(∩_∩)O~