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Finding the Fourth Proportional to 979.38, 1,469.42 and 431.50

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Solution

The fourth proportional to 979.38, 1,469.42 and 431.50 is: 647.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    979.38 : 1,469.42 = 431.50 : x
  2. Step 2: Convert to fraction form
    979.38/1,469.42 = 431.50/x
  3. Step 3: Cross multiply
    979.38x = 1,469.42 × 431.50
  4. Step 4: Simplify right side
    979.38x = 634,054.73
  5. Step 5: Solve for x
    x = 634,054.73/979.38
  6. Step 6: Final answer
    x = 647.40

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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.