作者shun28 (shun28)
看板Statistics
标题[问题] 最佳样本数估计母体平均
时间Sat Nov 27 15:42:45 2010
题目如下：
Dylan Jones kept careful records of the fuel efficiency of his new car.
After the first nine times the filled up the tank,hefound the mean was 23.4
miles per gallon with a sample standard deviation of 0.9 mpg.
（1）：在95％信心水准下，求解信赖区间？
第一小题没有问题
23.4＋2.306*(0.9/√9)=24.092
23.4-2.306*(0.9/√9)=22.708
α/2=0.025 T(8)=2.306
（2）:How many times should the fill his gas tank to obtain a margin of
error below 0.1 mpg?
解答算法：(2.306*0.9/0.1)^0.5=431
自己算法：(1.96*0.9/0.1)^0.5=312
关键问题在於解答带Ｔ值,而我是带入常态值
所以到底哪一个是正确的答案,请多多指教,谢谢.
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