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Finding the Fourth Proportional to 391.21, 539.82 and 216.55

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Solution

The fourth proportional to 391.21, 539.82 and 216.55 is: 298.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.21 : 539.82 = 216.55 : x
  2. Step 2: Convert to fraction form
    391.21/539.82 = 216.55/x
  3. Step 3: Cross multiply
    391.21x = 539.82 × 216.55
  4. Step 4: Simplify right side
    391.21x = 116,898.02
  5. Step 5: Solve for x
    x = 116,898.02/391.21
  6. Step 6: Final answer
    x = 298.81

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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.