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Finding the Fourth Proportional to 168.78, 252.90 and 138

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Solution

The fourth proportional to 168.78, 252.90 and 138 is: 206.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    168.78 : 252.90 = 138 : x
  2. Step 2: Convert to fraction form
    168.78/252.90 = 138/x
  3. Step 3: Cross multiply
    168.78x = 252.90 × 138
  4. Step 4: Simplify right side
    168.78x = 34,900.20
  5. Step 5: Solve for x
    x = 34,900.20/168.78
  6. Step 6: Final answer
    x = 206.78

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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.