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Finding the Fourth Proportional to 100.22, 138.05 and 76.86

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Solution

The fourth proportional to 100.22, 138.05 and 76.86 is: 105.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.22 : 138.05 = 76.86 : x
  2. Step 2: Convert to fraction form
    100.22/138.05 = 76.86/x
  3. Step 3: Cross multiply
    100.22x = 138.05 × 76.86
  4. Step 4: Simplify right side
    100.22x = 10,610.48
  5. Step 5: Solve for x
    x = 10,610.48/100.22
  6. Step 6: Final answer
    x = 105.87

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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.