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Finding the Fourth Proportional to 100.69, 138.85 and 84.09

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Solution

The fourth proportional to 100.69, 138.85 and 84.09 is: 115.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.69 : 138.85 = 84.09 : x
  2. Step 2: Convert to fraction form
    100.69/138.85 = 84.09/x
  3. Step 3: Cross multiply
    100.69x = 138.85 × 84.09
  4. Step 4: Simplify right side
    100.69x = 11,675.90
  5. Step 5: Solve for x
    x = 11,675.90/100.69
  6. Step 6: Final answer
    x = 115.96

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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.