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Finding the Fourth Proportional to 686.70, 947.49 and 391.95

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Solution

The fourth proportional to 686.70, 947.49 and 391.95 is: 540.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.70 : 947.49 = 391.95 : x
  2. Step 2: Convert to fraction form
    686.70/947.49 = 391.95/x
  3. Step 3: Cross multiply
    686.70x = 947.49 × 391.95
  4. Step 4: Simplify right side
    686.70x = 371,368.71
  5. Step 5: Solve for x
    x = 371,368.71/686.70
  6. Step 6: Final answer
    x = 540.80

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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.