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Finding the Fourth Proportional to 478.78, 660.83 and 312.70

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Solution

The fourth proportional to 478.78, 660.83 and 312.70 is: 431.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    478.78 : 660.83 = 312.70 : x
  2. Step 2: Convert to fraction form
    478.78/660.83 = 312.70/x
  3. Step 3: Cross multiply
    478.78x = 660.83 × 312.70
  4. Step 4: Simplify right side
    478.78x = 206,641.54
  5. Step 5: Solve for x
    x = 206,641.54/478.78
  6. Step 6: Final answer
    x = 431.60

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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.