Which number is one-half of the way between 2.2 and 8.5?

To find the number that is halfway between 2.2 and 8.5, we first calculate the average of the two numbers. Adding 2.2 and 8.5 gives us 10.7, and dividing by 2 gives us 5.35. Therefore, 5.35 is the number that is one-half of the way between 2.2 and 8.5.