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Finding the Fourth Proportional to 639.37, 882.12 and 390.61

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Solution

The fourth proportional to 639.37, 882.12 and 390.61 is: 538.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.37 : 882.12 = 390.61 : x
  2. Step 2: Convert to fraction form
    639.37/882.12 = 390.61/x
  3. Step 3: Cross multiply
    639.37x = 882.12 × 390.61
  4. Step 4: Simplify right side
    639.37x = 344,564.89
  5. Step 5: Solve for x
    x = 344,564.89/639.37
  6. Step 6: Final answer
    x = 538.91

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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.