We need:
Smallest and largest three-digit numbers divisible by 7, then find their average.
Smallest 3-digit number divisible by 7
Smallest 3-digit number = 100
100÷7=14remainder2
Next multiple:
7×15=105
So smallest = 105
Largest 3-digit number divisible by 7
Largest 3-digit number = 999
999÷7=142remainder5
So nearest lower multiple:
7×142=994
So largest = 994
Average
2105+994=21099=549.5
Final Answer: 549.5