Hypothesis test 问题

jaydark

The lengths of nails produced by a machine have a normal distribution with mean 2.5 cm. A random sample of 16 is selected from a drum containing a large number of these nails, The nails are measured and 13 are to found to have a length greater than 2.5cm. Test, at the 2.5 % significance level, whether the mean length of the nails in the drum is greater than 2.5 cm.
State where in test the information that the nails have a normal distribution is used


答案是 ： Ho u = 2.5
                                    H1 u> 2.5
&#160;                        &#160; &#160; &#160; &#160; &#160; &#160;at the end, the answer is 0.0106 < 0.025

没idea如何solve这个问题 。。。

flash

回复 1# jaydark


我个人觉得你所给的答案有问题，因为我们无法算出 sample 的 mean，又怎么能比较 mean 呢？

jaydark

对不起，这答案是我的朋友给我。。。 我会问去他清楚，再告诉你们。抱歉