Final answer:
The range of the extension cord lengths is 6 feet, so the largest length could be 14 feet.
Step-by-step explanation:
The range of a set of numbers is the difference between the largest and smallest values. In this case, the range of the lengths of the extension cords is given as 6 feet. If we subtract the smallest length (which is 8 feet) from the largest length, we get 6 feet. So, the largest length must be 14 feet. Therefore, the fifth size of extension cord could be 14 feet long.