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Finding the Fourth Proportional to 102.90, 142.02 and 81.06

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Solution

The fourth proportional to 102.90, 142.02 and 81.06 is: 111.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.90 : 142.02 = 81.06 : x
  2. Step 2: Convert to fraction form
    102.90/142.02 = 81.06/x
  3. Step 3: Cross multiply
    102.90x = 142.02 × 81.06
  4. Step 4: Simplify right side
    102.90x = 11,512.14
  5. Step 5: Solve for x
    x = 11,512.14/102.90
  6. Step 6: Final answer
    x = 111.88

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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.