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Finding the Fourth Proportional to 138.58, 207.89 and 83.78

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Solution

The fourth proportional to 138.58, 207.89 and 83.78 is: 125.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.58 : 207.89 = 83.78 : x
  2. Step 2: Convert to fraction form
    138.58/207.89 = 83.78/x
  3. Step 3: Cross multiply
    138.58x = 207.89 × 83.78
  4. Step 4: Simplify right side
    138.58x = 17,417.02
  5. Step 5: Solve for x
    x = 17,417.02/138.58
  6. Step 6: Final answer
    x = 125.68

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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.