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Finding the Fourth Proportional to 639.76, 959.31 and 331.78

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Solution

The fourth proportional to 639.76, 959.31 and 331.78 is: 497.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.76 : 959.31 = 331.78 : x
  2. Step 2: Convert to fraction form
    639.76/959.31 = 331.78/x
  3. Step 3: Cross multiply
    639.76x = 959.31 × 331.78
  4. Step 4: Simplify right side
    639.76x = 318,279.87
  5. Step 5: Solve for x
    x = 318,279.87/639.76
  6. Step 6: Final answer
    x = 497.50

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.