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Finding the Fourth Proportional to 639.63, 882.66 and 391.11

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Solution

The fourth proportional to 639.63, 882.66 and 391.11 is: 539.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.63 : 882.66 = 391.11 : x
  2. Step 2: Convert to fraction form
    639.63/882.66 = 391.11/x
  3. Step 3: Cross multiply
    639.63x = 882.66 × 391.11
  4. Step 4: Simplify right side
    639.63x = 345,217.15
  5. Step 5: Solve for x
    x = 345,217.15/639.63
  6. Step 6: Final answer
    x = 539.71

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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.