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Finding the Fourth Proportional to 87.31, 120.39 and 69.90

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Solution

The fourth proportional to 87.31, 120.39 and 69.90 is: 96.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.31 : 120.39 = 69.90 : x
  2. Step 2: Convert to fraction form
    87.31/120.39 = 69.90/x
  3. Step 3: Cross multiply
    87.31x = 120.39 × 69.90
  4. Step 4: Simplify right side
    87.31x = 8,414.55
  5. Step 5: Solve for x
    x = 8,414.55/87.31
  6. Step 6: Final answer
    x = 96.37

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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.