The problem most likely to involve irrational numbers is:
Finding the diameter of a circle based on the radius.
This is because the relationship between the diameter and radius of a circle involves the mathematical constant π (pi), which is an irrational number. If you find the diameter from the radius using the formula \(d = 2r\), while that result is rational if the radius is rational, the circumference of a circle (related to the diameter) involves π, which means calculations involving the circumference may result in irrational numbers as well.
In contrast, the other options typically involve rational numbers or can be expressed entirely within rational numbers based on the information given.