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Finding the Fourth Proportional to 90.38, 134.85 and 81.29

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Solution

The fourth proportional to 90.38, 134.85 and 81.29 is: 121.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.38 : 134.85 = 81.29 : x
  2. Step 2: Convert to fraction form
    90.38/134.85 = 81.29/x
  3. Step 3: Cross multiply
    90.38x = 134.85 × 81.29
  4. Step 4: Simplify right side
    90.38x = 10,961.28
  5. Step 5: Solve for x
    x = 10,961.28/90.38
  6. Step 6: Final answer
    x = 121.29

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.