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Finding the Fourth Proportional to 686.59, 947.28 and 391.87

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Solution

The fourth proportional to 686.59, 947.28 and 391.87 is: 540.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.59 : 947.28 = 391.87 : x
  2. Step 2: Convert to fraction form
    686.59/947.28 = 391.87/x
  3. Step 3: Cross multiply
    686.59x = 947.28 × 391.87
  4. Step 4: Simplify right side
    686.59x = 371,208.65
  5. Step 5: Solve for x
    x = 371,208.65/686.59
  6. Step 6: Final answer
    x = 540.66

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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.