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Finding the Fourth Proportional to 138.75, 207.78 and 126.42

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Solution

The fourth proportional to 138.75, 207.78 and 126.42 is: 189.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.75 : 207.78 = 126.42 : x
  2. Step 2: Convert to fraction form
    138.75/207.78 = 126.42/x
  3. Step 3: Cross multiply
    138.75x = 207.78 × 126.42
  4. Step 4: Simplify right side
    138.75x = 26,267.55
  5. Step 5: Solve for x
    x = 26,267.55/138.75
  6. Step 6: Final answer
    x = 189.32

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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.