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Finding the Fourth Proportional to 142.10, 211.86 and 138.91

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Solution

The fourth proportional to 142.10, 211.86 and 138.91 is: 207.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.10 : 211.86 = 138.91 : x
  2. Step 2: Convert to fraction form
    142.10/211.86 = 138.91/x
  3. Step 3: Cross multiply
    142.10x = 211.86 × 138.91
  4. Step 4: Simplify right side
    142.10x = 29,429.47
  5. Step 5: Solve for x
    x = 29,429.47/142.10
  6. Step 6: Final answer
    x = 207.10

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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.