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Finding the Fourth Proportional to 81.90, 122.69 and 63.78

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Solution

The fourth proportional to 81.90, 122.69 and 63.78 is: 95.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.90 : 122.69 = 63.78 : x
  2. Step 2: Convert to fraction form
    81.90/122.69 = 63.78/x
  3. Step 3: Cross multiply
    81.90x = 122.69 × 63.78
  4. Step 4: Simplify right side
    81.90x = 7,825.17
  5. Step 5: Solve for x
    x = 7,825.17/81.90
  6. Step 6: Final answer
    x = 95.55

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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.