Answer:
Sure. Here are the answers:
* Lower quartile (Q1): 12
* Upper quartile (Q3): 18
* Median: 15
* Interquartile range (IQR): Q3 - Q1 = 18 - 12 = 6
To find the lower quartile, we first need to order the data set from least to greatest:
```
10 12 14 15 18 20
```
Since there is an even number of data points, the median is the average of the two middle numbers. In this case, the two middle numbers are 14 and 15. Therefore, the median is (14 + 15) / 2 = 14.5.
The lower quartile is the median of the lower half of the data set. In this case, the lower half of the data set is:
```
10 12
```
The median of this data set is the average of the two middle numbers, which are 10 and 12. Therefore, the lower quartile is (10 + 12) / 2 = 11.
The upper quartile is the median of the upper half of the data set. In this case, the upper half of the data set is:
```
14 15 18 20
```
The median of this data set is the average of the two middle numbers, which are 14 and 15. Therefore, the upper quartile is (14 + 15) / 2 = 14.5.
The interquartile range is the difference between the upper and lower quartiles. In this case, the IQR is 14.5 - 11 = 3.5.
Explanation: