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Finding the Fourth Proportional to 686.81, 947.80 and 392.09

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Solution

The fourth proportional to 686.81, 947.80 and 392.09 is: 541.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.81 : 947.80 = 392.09 : x
  2. Step 2: Convert to fraction form
    686.81/947.80 = 392.09/x
  3. Step 3: Cross multiply
    686.81x = 947.80 × 392.09
  4. Step 4: Simplify right side
    686.81x = 371,622.90
  5. Step 5: Solve for x
    x = 371,622.90/686.81
  6. Step 6: Final answer
    x = 541.09

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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.