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Finding the Fourth Proportional to 689.85, 951.95 and 391.12

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Solution

The fourth proportional to 689.85, 951.95 and 391.12 is: 539.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.85 : 951.95 = 391.12 : x
  2. Step 2: Convert to fraction form
    689.85/951.95 = 391.12/x
  3. Step 3: Cross multiply
    689.85x = 951.95 × 391.12
  4. Step 4: Simplify right side
    689.85x = 372,326.68
  5. Step 5: Solve for x
    x = 372,326.68/689.85
  6. Step 6: Final answer
    x = 539.72

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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.