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Finding the Fourth Proportional to 686.20, 946.80 and 391.42

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Solution

The fourth proportional to 686.20, 946.80 and 391.42 is: 540.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.20 : 946.80 = 391.42 : x
  2. Step 2: Convert to fraction form
    686.20/946.80 = 391.42/x
  3. Step 3: Cross multiply
    686.20x = 946.80 × 391.42
  4. Step 4: Simplify right side
    686.20x = 370,596.46
  5. Step 5: Solve for x
    x = 370,596.46/686.20
  6. Step 6: Final answer
    x = 540.07

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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.