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Finding the Fourth Proportional to 128.13, 176.90 and 100.56

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Solution

The fourth proportional to 128.13, 176.90 and 100.56 is: 138.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.13 : 176.90 = 100.56 : x
  2. Step 2: Convert to fraction form
    128.13/176.90 = 100.56/x
  3. Step 3: Cross multiply
    128.13x = 176.90 × 100.56
  4. Step 4: Simplify right side
    128.13x = 17,788.56
  5. Step 5: Solve for x
    x = 17,788.56/128.13
  6. Step 6: Final answer
    x = 138.83

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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.