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Finding the Fourth Proportional to 979.72, 1,469.58 and 431.90

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Solution

The fourth proportional to 979.72, 1,469.58 and 431.90 is: 647.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    979.72 : 1,469.58 = 431.90 : x
  2. Step 2: Convert to fraction form
    979.72/1,469.58 = 431.90/x
  3. Step 3: Cross multiply
    979.72x = 1,469.58 × 431.90
  4. Step 4: Simplify right side
    979.72x = 634,709.44
  5. Step 5: Solve for x
    x = 634,709.44/979.72
  6. Step 6: Final answer
    x = 647.85

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.