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Finding the Fourth Proportional to 639.57, 882.41 and 390.90

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Solution

The fourth proportional to 639.57, 882.41 and 390.90 is: 539.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.57 : 882.41 = 390.90 : x
  2. Step 2: Convert to fraction form
    639.57/882.41 = 390.90/x
  3. Step 3: Cross multiply
    639.57x = 882.41 × 390.90
  4. Step 4: Simplify right side
    639.57x = 344,932.11
  5. Step 5: Solve for x
    x = 344,932.11/639.57
  6. Step 6: Final answer
    x = 539.32

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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.