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Finding the Fourth Proportional to 100.22, 138.20 and 81.74

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Solution

The fourth proportional to 100.22, 138.20 and 81.74 is: 112.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.22 : 138.20 = 81.74 : x
  2. Step 2: Convert to fraction form
    100.22/138.20 = 81.74/x
  3. Step 3: Cross multiply
    100.22x = 138.20 × 81.74
  4. Step 4: Simplify right side
    100.22x = 11,296.47
  5. Step 5: Solve for x
    x = 11,296.47/100.22
  6. Step 6: Final answer
    x = 112.72

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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.