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Finding the Fourth Proportional to 81.87, 122.58 and 57.78

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Solution

The fourth proportional to 81.87, 122.58 and 57.78 is: 86.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.87 : 122.58 = 57.78 : x
  2. Step 2: Convert to fraction form
    81.87/122.58 = 57.78/x
  3. Step 3: Cross multiply
    81.87x = 122.58 × 57.78
  4. Step 4: Simplify right side
    81.87x = 7,082.67
  5. Step 5: Solve for x
    x = 7,082.67/81.87
  6. Step 6: Final answer
    x = 86.51

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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.