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Finding the Fourth Proportional to 520.80, 780.80 and 260.88

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Solution

The fourth proportional to 520.80, 780.80 and 260.88 is: 391.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    520.80 : 780.80 = 260.88 : x
  2. Step 2: Convert to fraction form
    520.80/780.80 = 260.88/x
  3. Step 3: Cross multiply
    520.80x = 780.80 × 260.88
  4. Step 4: Simplify right side
    520.80x = 203,695.10
  5. Step 5: Solve for x
    x = 203,695.10/520.80
  6. Step 6: Final answer
    x = 391.12

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.