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Finding the Fourth Proportional to 142.38, 212.40 and 138.78

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Solution

The fourth proportional to 142.38, 212.40 and 138.78 is: 207.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.38 : 212.40 = 138.78 : x
  2. Step 2: Convert to fraction form
    142.38/212.40 = 138.78/x
  3. Step 3: Cross multiply
    142.38x = 212.40 × 138.78
  4. Step 4: Simplify right side
    142.38x = 29,476.87
  5. Step 5: Solve for x
    x = 29,476.87/142.38
  6. Step 6: Final answer
    x = 207.03

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.