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Finding the Fourth Proportional to 686.18, 947.02 and 391.47

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Solution

The fourth proportional to 686.18, 947.02 and 391.47 is: 540.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.18 : 947.02 = 391.47 : x
  2. Step 2: Convert to fraction form
    686.18/947.02 = 391.47/x
  3. Step 3: Cross multiply
    686.18x = 947.02 × 391.47
  4. Step 4: Simplify right side
    686.18x = 370,729.92
  5. Step 5: Solve for x
    x = 370,729.92/686.18
  6. Step 6: Final answer
    x = 540.28

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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.