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Finding the Fourth Proportional to 87.72, 120.85 and 73.90

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Solution

The fourth proportional to 87.72, 120.85 and 73.90 is: 101.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.72 : 120.85 = 73.90 : x
  2. Step 2: Convert to fraction form
    87.72/120.85 = 73.90/x
  3. Step 3: Cross multiply
    87.72x = 120.85 × 73.90
  4. Step 4: Simplify right side
    87.72x = 8,930.82
  5. Step 5: Solve for x
    x = 8,930.82/87.72
  6. Step 6: Final answer
    x = 101.81

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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.