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Finding the Fourth Proportional to 686.63, 947.53 and 391.90

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Solution

The fourth proportional to 686.63, 947.53 and 391.90 is: 540.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.63 : 947.53 = 391.90 : x
  2. Step 2: Convert to fraction form
    686.63/947.53 = 391.90/x
  3. Step 3: Cross multiply
    686.63x = 947.53 × 391.90
  4. Step 4: Simplify right side
    686.63x = 371,337.01
  5. Step 5: Solve for x
    x = 371,337.01/686.63
  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.