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Finding the Fourth Proportional to 87.56, 121.12 and 81.75

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Solution

The fourth proportional to 87.56, 121.12 and 81.75 is: 113.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.56 : 121.12 = 81.75 : x
  2. Step 2: Convert to fraction form
    87.56/121.12 = 81.75/x
  3. Step 3: Cross multiply
    87.56x = 121.12 × 81.75
  4. Step 4: Simplify right side
    87.56x = 9,901.36
  5. Step 5: Solve for x
    x = 9,901.36/87.56
  6. Step 6: Final answer
    x = 113.09

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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.