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Finding the Fourth Proportional to 639.78, 882.96 and 391.08

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Solution

The fourth proportional to 639.78, 882.96 and 391.08 is: 539.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.78 : 882.96 = 391.08 : x
  2. Step 2: Convert to fraction form
    639.78/882.96 = 391.08/x
  3. Step 3: Cross multiply
    639.78x = 882.96 × 391.08
  4. Step 4: Simplify right side
    639.78x = 345,308.00
  5. Step 5: Solve for x
    x = 345,308.00/639.78
  6. Step 6: Final answer
    x = 539.73

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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.