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Finding the Fourth Proportional to 100.10, 138.09 and 81.75

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Solution

The fourth proportional to 100.10, 138.09 and 81.75 is: 112.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.10 : 138.09 = 81.75 : x
  2. Step 2: Convert to fraction form
    100.10/138.09 = 81.75/x
  3. Step 3: Cross multiply
    100.10x = 138.09 × 81.75
  4. Step 4: Simplify right side
    100.10x = 11,288.86
  5. Step 5: Solve for x
    x = 11,288.86/100.10
  6. Step 6: Final answer
    x = 112.78

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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.