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Finding the Fourth Proportional to 81.89, 122.87 and 51.45

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Solution

The fourth proportional to 81.89, 122.87 and 51.45 is: 77.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.89 : 122.87 = 51.45 : x
  2. Step 2: Convert to fraction form
    81.89/122.87 = 51.45/x
  3. Step 3: Cross multiply
    81.89x = 122.87 × 51.45
  4. Step 4: Simplify right side
    81.89x = 6,321.66
  5. Step 5: Solve for x
    x = 6,321.66/81.89
  6. Step 6: Final answer
    x = 77.20

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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.