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Finding the Fourth Proportional to 686.44, 947.28 and 391.72

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Solution

The fourth proportional to 686.44, 947.28 and 391.72 is: 540.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.44 : 947.28 = 391.72 : x
  2. Step 2: Convert to fraction form
    686.44/947.28 = 391.72/x
  3. Step 3: Cross multiply
    686.44x = 947.28 × 391.72
  4. Step 4: Simplify right side
    686.44x = 371,068.52
  5. Step 5: Solve for x
    x = 371,068.52/686.44
  6. Step 6: Final answer
    x = 540.57

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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.