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Finding the Fourth Proportional to 20.61, 30.87 and 12.57

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Solution

The fourth proportional to 20.61, 30.87 and 12.57 is: 18.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.61 : 30.87 = 12.57 : x
  2. Step 2: Convert to fraction form
    20.61/30.87 = 12.57/x
  3. Step 3: Cross multiply
    20.61x = 30.87 × 12.57
  4. Step 4: Simplify right side
    20.61x = 388.04
  5. Step 5: Solve for x
    x = 388.04/20.61
  6. Step 6: Final answer
    x = 18.83

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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.