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Finding the Fourth Proportional to 638.78, 957.20 and 394.92

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Solution

The fourth proportional to 638.78, 957.20 and 394.92 is: 591.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.78 : 957.20 = 394.92 : x
  2. Step 2: Convert to fraction form
    638.78/957.20 = 394.92/x
  3. Step 3: Cross multiply
    638.78x = 957.20 × 394.92
  4. Step 4: Simplify right side
    638.78x = 378,015.45
  5. Step 5: Solve for x
    x = 378,015.45/638.78
  6. Step 6: Final answer
    x = 591.78

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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.