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Finding the Fourth Proportional to 81.80, 122.39 and 51.42

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Solution

The fourth proportional to 81.80, 122.39 and 51.42 is: 76.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.80 : 122.39 = 51.42 : x
  2. Step 2: Convert to fraction form
    81.80/122.39 = 51.42/x
  3. Step 3: Cross multiply
    81.80x = 122.39 × 51.42
  4. Step 4: Simplify right side
    81.80x = 6,293.29
  5. Step 5: Solve for x
    x = 6,293.29/81.80
  6. Step 6: Final answer
    x = 76.94

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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.