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Finding the Fourth Proportional to 686.82, 947.61 and 391.98

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Solution

The fourth proportional to 686.82, 947.61 and 391.98 is: 540.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.82 : 947.61 = 391.98 : x
  2. Step 2: Convert to fraction form
    686.82/947.61 = 391.98/x
  3. Step 3: Cross multiply
    686.82x = 947.61 × 391.98
  4. Step 4: Simplify right side
    686.82x = 371,444.17
  5. Step 5: Solve for x
    x = 371,444.17/686.82
  6. Step 6: Final answer
    x = 540.82

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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.