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Finding the Fourth Proportional to 138.21, 207.09 and 69.72

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Solution

The fourth proportional to 138.21, 207.09 and 69.72 is: 104.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.21 : 207.09 = 69.72 : x
  2. Step 2: Convert to fraction form
    138.21/207.09 = 69.72/x
  3. Step 3: Cross multiply
    138.21x = 207.09 × 69.72
  4. Step 4: Simplify right side
    138.21x = 14,438.31
  5. Step 5: Solve for x
    x = 14,438.31/138.21
  6. Step 6: Final answer
    x = 104.47

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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.