Answer:
0
Step-by-step explanation:
The sorted data set is ...
1 2 3 3 5 7 8 9
The median is the average of the middle two numbers: (3+5)/2 = 4.
Replacing one of the 3s with a 1 makes the data set be ...
1 1 2 3 5 7 8 9
The average of the middle two numbers is (3+5)/2 = 4.
The median increases by 4 - 4 = 0.
