What is the range of the set of numbers: 4, 8, 6, 5?

To determine the range of a set of numbers, one must subtract the smallest number in the set from the largest number.

In the set provided: 4, 8, 6, 5, the largest number is 8 and the smallest number is 4. Therefore, the range can be calculated as follows:

Range = Largest Number - Smallest Number

Range = 8 - 4 = 4.

This calculation shows that the difference between the highest and lowest values in the set is 4, which defines the spread of the numbers. Thus, the correct answer is that the range of the set of numbers is 4.