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Finding the Fourth Proportional to 81.58, 122.35 and 76.81

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Solution

The fourth proportional to 81.58, 122.35 and 76.81 is: 115.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.58 : 122.35 = 76.81 : x
  2. Step 2: Convert to fraction form
    81.58/122.35 = 76.81/x
  3. Step 3: Cross multiply
    81.58x = 122.35 × 76.81
  4. Step 4: Simplify right side
    81.58x = 9,397.70
  5. Step 5: Solve for x
    x = 9,397.70/81.58
  6. Step 6: Final answer
    x = 115.20

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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.