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Finding the Fourth Proportional to 13.72, 20.61 and 12.40

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Solution

The fourth proportional to 13.72, 20.61 and 12.40 is: 18.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.72 : 20.61 = 12.40 : x
  2. Step 2: Convert to fraction form
    13.72/20.61 = 12.40/x
  3. Step 3: Cross multiply
    13.72x = 20.61 × 12.40
  4. Step 4: Simplify right side
    13.72x = 255.56
  5. Step 5: Solve for x
    x = 255.56/13.72
  6. Step 6: Final answer
    x = 18.63

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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.