老师，请问FRM一级习题集的 Q624 怎么判断哪个选项的DV01 是negative的； 像PO的话，利率下降，不应该提前偿还更多的本金，从而导致PO价格上升， 而IO的话，则和PO相反

请问老师这个题怎么做

请问semiannual payment but quarterly compounding 这个题怎么做？

这题是怎么做出来的 In a metal fabrication process, metal rods are produced that have an average length of 20.5 metres with a standard deviation of 2.3 metres. A quality control specialist collects a random sample of 30 rods and measures their lengths. 问题Suppose the resulting sample mean is 19.5 metres. Do you think that this sample result is unusually small? Explain. 答案：We have a random sample of metal rods drawn from a much larger population. A sample mean of only 19.5 metres is about 2.38 standard deviations below what we expect. The sample mean of 19.5 metres is unusually small.

In a metal fabrication process, metal rods are produced that have an average length of 20.5 metres with a standard deviation of 2.3 metres. A quality control specialist collects a random sample of 30 rods and measures their lengths. 问题：Suppose the resulting sample mean is 19.5 metres. Do you think that this sample result is unusually small? Explain. 答案：We have a random sample of metal rods drawn from a much larger population. A sample mean of only 19.5 metres is about 2.38 standard deviations below what we expect. The sample mean of 19.5 metres is unusually small. 老师我想请问这个题的答案怎么出来的，2.38这个数字怎么来的

这里的correlation是指的线性相关吗？？求解

这里的correlation是指的线性相关吗？？求解

这里的correlation是指的线性相关吗？

这里的correlation是指的线性相关吗？

这里的correlation是指的线性相关吗？