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Finding the Fourth Proportional to 256.80, 391.20 and 256.80

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Solution

The fourth proportional to 256.80, 391.20 and 256.80 is: 391.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    256.80 : 391.20 = 256.80 : x
  2. Step 2: Convert to fraction form
    256.80/391.20 = 256.80/x
  3. Step 3: Cross multiply
    256.80x = 391.20 × 256.80
  4. Step 4: Simplify right side
    256.80x = 100,460.16
  5. Step 5: Solve for x
    x = 100,460.16/256.80
  6. Step 6: Final answer
    x = 391.20

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Why These Related Problems?

These problems maintain the same ratio (1.52) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.