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Finding the Fourth Proportional to 154.50, 212.79 and 138.90

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Solution

The fourth proportional to 154.50, 212.79 and 138.90 is: 191.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    154.50 : 212.79 = 138.90 : x
  2. Step 2: Convert to fraction form
    154.50/212.79 = 138.90/x
  3. Step 3: Cross multiply
    154.50x = 212.79 × 138.90
  4. Step 4: Simplify right side
    154.50x = 29,556.53
  5. Step 5: Solve for x
    x = 29,556.53/154.50
  6. Step 6: Final answer
    x = 191.30

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.