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Finding the Fourth Proportional to 128.34, 177.13 and 81.75

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Solution

The fourth proportional to 128.34, 177.13 and 81.75 is: 112.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.34 : 177.13 = 81.75 : x
  2. Step 2: Convert to fraction form
    128.34/177.13 = 81.75/x
  3. Step 3: Cross multiply
    128.34x = 177.13 × 81.75
  4. Step 4: Simplify right side
    128.34x = 14,481.14
  5. Step 5: Solve for x
    x = 14,481.14/128.34
  6. Step 6: Final answer
    x = 112.83

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.