问题如下：
For the following data:
a. What is the median?
b. What is the IQR?
选项：
解释：
a. The first step is to rank order the observations.
From here, we anchor the first observation at 0% and the last at 100%, equally spacing the in-between val-ues. The divisions here will be 100/n-1 = 20%:
The median (50%) lies exactly half way between the third and fourth ranked observations. Therefore:
Median=(0.28+0.38)/2=0.33
b. This requires calculating the 25% and 75% levels.
The 25% level is 5/20 = 25% of the way between ranked observations 2 and 3. Therefore: q25% = 0.75 * 0.27 + 0.25 * 0.28 = 0.2725
Similarly, the 75% level is 75% of the way between observations 4 and 5: q75% = 0.25 * 0.38 + 0.75 * 0.43 = 0.4175
Thus, IQR = (0.2725, 0.4175).
没有看明白为什么25%是5/20，为什么是2和3的观察值，75%为什么又找的是4和5的观察值？
