Iknow a, but i need with b, c, and d

Step-by-step explanation:

So, to start, we need to label all the values. This is

16, 17, 17, 17, 18, 18 , 18 , 18, 18, 18, 19, 19, and 20.

The Lower Quartile can be found if you know the median. The median in this case is 18. So, the Lower Quartile is just median between the median and the lowest number. So it is the median between 18 and 16. Not average, but the median in the set. In this case it is 17. The Upper Quartile is the same except now it is between the median and highest value, or 18.5. The IQR is found by subtracting the Upper by the Lower, or 18.5-17, or 1.5.

is there any photos or whatever?