Answer:

Explanation:
The given data set is:
7.7, 8.4, 9, 8, 6.9
In order to find the Interquartile range, firstly arrange the given data set in ascending order, we have
6.9, 7.7, 8, 8.4, 9
Now, The median is the middle term in the arranged data set that is 8, and The lower half of data is the set below the median that is:
6.9, 7.7
The median for the lower half of data 6.9 , 7.7 is the lower or first quartile that is

And, The upper half of data is the set above the median that is:
8.4, 9
The median for the upper half of data 8.4 , 9 is the upper or third quartile that is
.
Now, The interquartile range is the difference between the first quartile 7.3 and the third quartile 8.7 that is:

.