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Finding the Fourth Proportional to 87.60, 120.85 and 54.87

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Solution

The fourth proportional to 87.60, 120.85 and 54.87 is: 75.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.60 : 120.85 = 54.87 : x
  2. Step 2: Convert to fraction form
    87.60/120.85 = 54.87/x
  3. Step 3: Cross multiply
    87.60x = 120.85 × 54.87
  4. Step 4: Simplify right side
    87.60x = 6,631.04
  5. Step 5: Solve for x
    x = 6,631.04/87.60
  6. Step 6: Final answer
    x = 75.70

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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.