Which rational number is one-half of the way between 2 and 6.5: 2.25, 4.25, 4.5, or 4.75?

The question is simply asking for the average or the arithmetic mean between 2 and 6.5. To find the average, add up the numbers and divide by 2. This is shown below,

a = (2 + 6.5) / 2

The value of a is 4.25. Thus, the answer is the third choice.