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Finding the Fourth Proportional to 102.12, 140.72 and 81.32

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Solution

The fourth proportional to 102.12, 140.72 and 81.32 is: 112.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.12 : 140.72 = 81.32 : x
  2. Step 2: Convert to fraction form
    102.12/140.72 = 81.32/x
  3. Step 3: Cross multiply
    102.12x = 140.72 × 81.32
  4. Step 4: Simplify right side
    102.12x = 11,443.35
  5. Step 5: Solve for x
    x = 11,443.35/102.12
  6. Step 6: Final answer
    x = 112.06

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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.