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Finding the Fourth Proportional to 391.20, 535.85 and 390.12

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Solution

The fourth proportional to 391.20, 535.85 and 390.12 is: 534.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.20 : 535.85 = 390.12 : x
  2. Step 2: Convert to fraction form
    391.20/535.85 = 390.12/x
  3. Step 3: Cross multiply
    391.20x = 535.85 × 390.12
  4. Step 4: Simplify right side
    391.20x = 209,043.85
  5. Step 5: Solve for x
    x = 209,043.85/391.20
  6. Step 6: Final answer
    x = 534.37

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.