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Finding the Fourth Proportional to 87.72, 120.88 and 81.48

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Solution

The fourth proportional to 87.72, 120.88 and 81.48 is: 112.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.72 : 120.88 = 81.48 : x
  2. Step 2: Convert to fraction form
    87.72/120.88 = 81.48/x
  3. Step 3: Cross multiply
    87.72x = 120.88 × 81.48
  4. Step 4: Simplify right side
    87.72x = 9,849.30
  5. Step 5: Solve for x
    x = 9,849.30/87.72
  6. Step 6: Final answer
    x = 112.28

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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.