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Finding the Fourth Proportional to 686.66, 947.70 and 391.95

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Solution

The fourth proportional to 686.66, 947.70 and 391.95 is: 540.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.66 : 947.70 = 391.95 : x
  2. Step 2: Convert to fraction form
    686.66/947.70 = 391.95/x
  3. Step 3: Cross multiply
    686.66x = 947.70 × 391.95
  4. Step 4: Simplify right side
    686.66x = 371,451.02
  5. Step 5: Solve for x
    x = 371,451.02/686.66
  6. Step 6: Final answer
    x = 540.96

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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.