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Finding the Fourth Proportional to 979.92, 1,469.76 and 321.78

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Solution

The fourth proportional to 979.92, 1,469.76 and 321.78 is: 482.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    979.92 : 1,469.76 = 321.78 : x
  2. Step 2: Convert to fraction form
    979.92/1,469.76 = 321.78/x
  3. Step 3: Cross multiply
    979.92x = 1,469.76 × 321.78
  4. Step 4: Simplify right side
    979.92x = 472,939.37
  5. Step 5: Solve for x
    x = 472,939.37/979.92
  6. Step 6: Final answer
    x = 482.63

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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.