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Finding the Fourth Proportional to 639.78, 883.24 and 391.14

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Solution

The fourth proportional to 639.78, 883.24 and 391.14 is: 539.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.78 : 883.24 = 391.14 : x
  2. Step 2: Convert to fraction form
    639.78/883.24 = 391.14/x
  3. Step 3: Cross multiply
    639.78x = 883.24 × 391.14
  4. Step 4: Simplify right side
    639.78x = 345,470.49
  5. Step 5: Solve for x
    x = 345,470.49/639.78
  6. Step 6: Final answer
    x = 539.98

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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.