A calculator manufacturing company checks 500 calculator units, and 25 of them have non-functioning keys. Approximate the relative frequency of a non-defective unit from this batch of items. Express your answer in the simplest form of a fraction.(1 point)
Relative frequency of non-defective units = (Total units - Non-defective units) / Total units
= (500 - 25) / 500
= 475 / 500
= 19 / 20
Therefore, the relative frequency of a non-defective unit from this batch of items is 19/20.