In an examination, A got 25% more marks than B, B got 10% less marks than C, and C got 25% more marks than D, D got 320 out of 500, then A got how many marks?

Given the relationships among the marks of students A, B, C, and D, we can determine the marks for A step-by-step starting from D.

1. **Determine the marks for D:**
   \( D = 320 \)

2. **Calculate the marks for C:**
   \( C \) got 25% more marks than \( D \).
   \[
   C = D \times \left(1 + \frac{25}{100}\right) = 320 \times 1.25 = 400
   \]

3. **Calculate the marks for B:**
   \( B \) got 10% less marks than \( C \).
   \[
   B = C \times \left(1 - \frac{10}{100}\right) = 400 \times 0.90 = 360
   \]

4. **Calculate the marks for A:**
   \( A \) got 25% more marks than \( B \).
   \[
   A = B \times \left(1 + \frac{25}{100}\right) = 360 \times 1.25 = 450
   \]

Thus, A got **450** marks.

Would you like more details or have any questions? Here are some related questions you might find useful:

1. How do you convert percentages to decimals for calculations?
2. What are other ways to express percentage increases and decreases?
3. How can you verify the relationships among marks if given different starting values?
4. How can you use proportional reasoning to solve similar problems?
5. What are some real-world applications of percentage increase and decrease?
6. Can you explain the concept of compound percentage changes?
7. How would the solution change if D's total marks were different?
8. How do you handle multiple percentage changes in sequence?

**Tip:** When dealing with percentage increases or decreases, always convert the percentage to a decimal form to simplify calculations.

Learn how to calculate the marks for students A, B, C, and D in an examination using percentage increase and decrease. Step-by-step solution provided starting from D's marks of 320 out of 500. Suitable for Grades 7-9.

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