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Finding the Fourth Proportional to 686.85, 947.59 and 391.95

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Solution

The fourth proportional to 686.85, 947.59 and 391.95 is: 540.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.85 : 947.59 = 391.95 : x
  2. Step 2: Convert to fraction form
    686.85/947.59 = 391.95/x
  3. Step 3: Cross multiply
    686.85x = 947.59 × 391.95
  4. Step 4: Simplify right side
    686.85x = 371,407.70
  5. Step 5: Solve for x
    x = 371,407.70/686.85
  6. Step 6: Final answer
    x = 540.74

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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.