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Finding the Fourth Proportional to 639.81, 959.90 and 331.87

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Solution

The fourth proportional to 639.81, 959.90 and 331.87 is: 497.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.81 : 959.90 = 331.87 : x
  2. Step 2: Convert to fraction form
    639.81/959.90 = 331.87/x
  3. Step 3: Cross multiply
    639.81x = 959.90 × 331.87
  4. Step 4: Simplify right side
    639.81x = 318,562.01
  5. Step 5: Solve for x
    x = 318,562.01/639.81
  6. Step 6: Final answer
    x = 497.90

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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.