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Finding the Fourth Proportional to 81.76, 122.96 and 76.48

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Solution

The fourth proportional to 81.76, 122.96 and 76.48 is: 115.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.76 : 122.96 = 76.48 : x
  2. Step 2: Convert to fraction form
    81.76/122.96 = 76.48/x
  3. Step 3: Cross multiply
    81.76x = 122.96 × 76.48
  4. Step 4: Simplify right side
    81.76x = 9,403.98
  5. Step 5: Solve for x
    x = 9,403.98/81.76
  6. Step 6: Final answer
    x = 115.02

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.