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Finding the Fourth Proportional to 979.20, 1,469.13 and 431.77

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Solution

The fourth proportional to 979.20, 1,469.13 and 431.77 is: 647.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    979.20 : 1,469.13 = 431.77 : x
  2. Step 2: Convert to fraction form
    979.20/1,469.13 = 431.77/x
  3. Step 3: Cross multiply
    979.20x = 1,469.13 × 431.77
  4. Step 4: Simplify right side
    979.20x = 634,326.26
  5. Step 5: Solve for x
    x = 634,326.26/979.20
  6. Step 6: Final answer
    x = 647.80

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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.