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Finding the Fourth Proportional to 391.20, 539.88 and 225.40

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Solution

The fourth proportional to 391.20, 539.88 and 225.40 is: 311.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.20 : 539.88 = 225.40 : x
  2. Step 2: Convert to fraction form
    391.20/539.88 = 225.40/x
  3. Step 3: Cross multiply
    391.20x = 539.88 × 225.40
  4. Step 4: Simplify right side
    391.20x = 121,688.95
  5. Step 5: Solve for x
    x = 121,688.95/391.20
  6. Step 6: Final answer
    x = 311.07

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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.