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Finding the Fourth Proportional to 639.65, 882.68 and 391.38

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Solution

The fourth proportional to 639.65, 882.68 and 391.38 is: 540.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.65 : 882.68 = 391.38 : x
  2. Step 2: Convert to fraction form
    639.65/882.68 = 391.38/x
  3. Step 3: Cross multiply
    639.65x = 882.68 × 391.38
  4. Step 4: Simplify right side
    639.65x = 345,463.30
  5. Step 5: Solve for x
    x = 345,463.30/639.65
  6. Step 6: Final answer
    x = 540.08

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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.