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Finding the Fourth Proportional to 669.78, 997.11 and 639.90

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Solution

The fourth proportional to 669.78, 997.11 and 639.90 is: 952.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    669.78 : 997.11 = 639.90 : x
  2. Step 2: Convert to fraction form
    669.78/997.11 = 639.90/x
  3. Step 3: Cross multiply
    669.78x = 997.11 × 639.90
  4. Step 4: Simplify right side
    669.78x = 638,050.69
  5. Step 5: Solve for x
    x = 638,050.69/669.78
  6. Step 6: Final answer
    x = 952.63

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.