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Finding the Fourth Proportional to 280.78, 421.17 and 72.55

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Solution

The fourth proportional to 280.78, 421.17 and 72.55 is: 108.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.78 : 421.17 = 72.55 : x
  2. Step 2: Convert to fraction form
    280.78/421.17 = 72.55/x
  3. Step 3: Cross multiply
    280.78x = 421.17 × 72.55
  4. Step 4: Simplify right side
    280.78x = 30,553.77
  5. Step 5: Solve for x
    x = 30,553.77/280.78
  6. Step 6: Final answer
    x = 108.82

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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.