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Finding the Fourth Proportional to 639.87, 959.90 and 331.76

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Solution

The fourth proportional to 639.87, 959.90 and 331.76 is: 497.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.87 : 959.90 = 331.76 : x
  2. Step 2: Convert to fraction form
    639.87/959.90 = 331.76/x
  3. Step 3: Cross multiply
    639.87x = 959.90 × 331.76
  4. Step 4: Simplify right side
    639.87x = 318,449.97
  5. Step 5: Solve for x
    x = 318,449.97/639.87
  6. Step 6: Final answer
    x = 497.68

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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.