1. **State the problem:** Calculate the percentage weight (grade) of 25 marks if the total marks are 25. 2. **Formula used:** Percentage = $\frac{\text{Obtained marks}}{\text{Total marks}} \times 100$ 3. **Apply the formula:** Here, Obtained marks = 25, Total marks = 25 $$\text{Percentage} = \frac{25}{25} \times 100 = 100\%$$ 4. **Explanation:** Since the student scored all 25 marks out of 25, the percentage is 100%. This means full marks were obtained. 5. **Final answer:** The percentage weight (grade) for 25 marks out of 25 is **100%**.