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Finding the Fourth Proportional to 138.90, 207.87 and 102.78

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Solution

The fourth proportional to 138.90, 207.87 and 102.78 is: 153.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.90 : 207.87 = 102.78 : x
  2. Step 2: Convert to fraction form
    138.90/207.87 = 102.78/x
  3. Step 3: Cross multiply
    138.90x = 207.87 × 102.78
  4. Step 4: Simplify right side
    138.90x = 21,364.88
  5. Step 5: Solve for x
    x = 21,364.88/138.90
  6. Step 6: Final answer
    x = 153.81

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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.