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Finding the Fourth Proportional to 686.34, 947.18 and 391.70

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Solution

The fourth proportional to 686.34, 947.18 and 391.70 is: 540.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.34 : 947.18 = 391.70 : x
  2. Step 2: Convert to fraction form
    686.34/947.18 = 391.70/x
  3. Step 3: Cross multiply
    686.34x = 947.18 × 391.70
  4. Step 4: Simplify right side
    686.34x = 371,010.41
  5. Step 5: Solve for x
    x = 371,010.41/686.34
  6. Step 6: Final answer
    x = 540.56

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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.