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Finding the Fourth Proportional to 90.90, 136.08 and 81.90

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Solution

The fourth proportional to 90.90, 136.08 and 81.90 is: 122.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.90 : 136.08 = 81.90 : x
  2. Step 2: Convert to fraction form
    90.90/136.08 = 81.90/x
  3. Step 3: Cross multiply
    90.90x = 136.08 × 81.90
  4. Step 4: Simplify right side
    90.90x = 11,144.95
  5. Step 5: Solve for x
    x = 11,144.95/90.90
  6. Step 6: Final answer
    x = 122.61

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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.