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Finding the Fourth Proportional to 391.20, 539.85 and 216.55

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Solution

The fourth proportional to 391.20, 539.85 and 216.55 is: 298.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.20 : 539.85 = 216.55 : x
  2. Step 2: Convert to fraction form
    391.20/539.85 = 216.55/x
  3. Step 3: Cross multiply
    391.20x = 539.85 × 216.55
  4. Step 4: Simplify right side
    391.20x = 116,904.52
  5. Step 5: Solve for x
    x = 116,904.52/391.20
  6. Step 6: Final answer
    x = 298.84

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.