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Finding the Fourth Proportional to 154.20, 231.15 and 138

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Solution

The fourth proportional to 154.20, 231.15 and 138 is: 206.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    154.20 : 231.15 = 138 : x
  2. Step 2: Convert to fraction form
    154.20/231.15 = 138/x
  3. Step 3: Cross multiply
    154.20x = 231.15 × 138
  4. Step 4: Simplify right side
    154.20x = 31,898.70
  5. Step 5: Solve for x
    x = 31,898.70/154.20
  6. Step 6: Final answer
    x = 206.87

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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.