Final answer:
The number that is halfway between 63.0 and 63.1 is 63.05, calculated by taking the average of the two numbers.
Step-by-step explanation:
To find the number that is halfway between 63.0 and 63.1, we calculate the average of the two numbers. This is done by adding the given numbers together and dividing by 2:
(63.0 + 63.1) / 2 = 126.1 / 2 = 63.05
Therefore, the number that is halfway between 63.0 and 63.1 is 63.05. So, the correct answer is a) 63.05.