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Finding the Fourth Proportional to 128.10, 191.84 and 81.83

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Solution

The fourth proportional to 128.10, 191.84 and 81.83 is: 122.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.10 : 191.84 = 81.83 : x
  2. Step 2: Convert to fraction form
    128.10/191.84 = 81.83/x
  3. Step 3: Cross multiply
    128.10x = 191.84 × 81.83
  4. Step 4: Simplify right side
    128.10x = 15,696.90
  5. Step 5: Solve for x
    x = 15,696.90/128.10
  6. Step 6: Final answer
    x = 122.54

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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.