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Finding the Fourth Proportional to 278.92, 418.38 and 86.55

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Solution

The fourth proportional to 278.92, 418.38 and 86.55 is: 129.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.92 : 418.38 = 86.55 : x
  2. Step 2: Convert to fraction form
    278.92/418.38 = 86.55/x
  3. Step 3: Cross multiply
    278.92x = 418.38 × 86.55
  4. Step 4: Simplify right side
    278.92x = 36,210.79
  5. Step 5: Solve for x
    x = 36,210.79/278.92
  6. Step 6: Final answer
    x = 129.83

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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.