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Finding the Fourth Proportional to 686.61, 947.57 and 391.88

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Solution

The fourth proportional to 686.61, 947.57 and 391.88 is: 540.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.61 : 947.57 = 391.88 : x
  2. Step 2: Convert to fraction form
    686.61/947.57 = 391.88/x
  3. Step 3: Cross multiply
    686.61x = 947.57 × 391.88
  4. Step 4: Simplify right side
    686.61x = 371,327.03
  5. Step 5: Solve for x
    x = 371,327.03/686.61
  6. Step 6: Final answer
    x = 540.81

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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.