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Finding the Fourth Proportional to 87.76, 120.90 and 81.52

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Solution

The fourth proportional to 87.76, 120.90 and 81.52 is: 112.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.76 : 120.90 = 81.52 : x
  2. Step 2: Convert to fraction form
    87.76/120.90 = 81.52/x
  3. Step 3: Cross multiply
    87.76x = 120.90 × 81.52
  4. Step 4: Simplify right side
    87.76x = 9,855.77
  5. Step 5: Solve for x
    x = 9,855.77/87.76
  6. Step 6: Final answer
    x = 112.30

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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.