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Finding the Fourth Proportional to 142.38, 213.57 and 81.42

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Solution

The fourth proportional to 142.38, 213.57 and 81.42 is: 122.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.38 : 213.57 = 81.42 : x
  2. Step 2: Convert to fraction form
    142.38/213.57 = 81.42/x
  3. Step 3: Cross multiply
    142.38x = 213.57 × 81.42
  4. Step 4: Simplify right side
    142.38x = 17,388.87
  5. Step 5: Solve for x
    x = 17,388.87/142.38
  6. Step 6: Final answer
    x = 122.13

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.