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Finding the Fourth Proportional to 686.80, 947.52 and 391.88

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Solution

The fourth proportional to 686.80, 947.52 and 391.88 is: 540.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.80 : 947.52 = 391.88 : x
  2. Step 2: Convert to fraction form
    686.80/947.52 = 391.88/x
  3. Step 3: Cross multiply
    686.80x = 947.52 × 391.88
  4. Step 4: Simplify right side
    686.80x = 371,314.14
  5. Step 5: Solve for x
    x = 371,314.14/686.80
  6. Step 6: Final answer
    x = 540.64

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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.