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Finding the Fourth Proportional to 20.47, 30.72 and 12.43

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Solution

The fourth proportional to 20.47, 30.72 and 12.43 is: 18.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.47 : 30.72 = 12.43 : x
  2. Step 2: Convert to fraction form
    20.47/30.72 = 12.43/x
  3. Step 3: Cross multiply
    20.47x = 30.72 × 12.43
  4. Step 4: Simplify right side
    20.47x = 381.85
  5. Step 5: Solve for x
    x = 381.85/20.47
  6. Step 6: Final answer
    x = 18.65

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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.