Final answer:
Each transformer tap changes the voltage by a small percentage, typically fixed, such as the 2.5% indicated here. The question's context does not provide a complete answer but the references suggest a possible percentage change using scientific notation.
Step-by-step explanation:
The question you're asking relates to the concept of transformer taps, which are used in electricity and Physics to adjust the voltage level. Each tap changes the secondary voltage by a certain percentage, and in this case, by 2.5%. However, the question seems to be incomplete as it asks for another percentage which is not provided in the context. Usually, transformer taps are fixed at a few percent change in either direction for each tap operation. Your references (c) and (d) do not directly answer the question but suggest that they might be setting up for a calculation of a percentage change using scientific notation and indicative of a slight percentage increase or decrease.
So, while a direct answer to the provided question is not possible due to its incomplete nature, we can confirm that tap adjustments usually involve a small percentage change of the voltage, potentially similar to the figures provided in (c) and (d).