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Finding the Fourth Proportional to 20.40, 28.12 and 13.92

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Solution

The fourth proportional to 20.40, 28.12 and 13.92 is: 19.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.40 : 28.12 = 13.92 : x
  2. Step 2: Convert to fraction form
    20.40/28.12 = 13.92/x
  3. Step 3: Cross multiply
    20.40x = 28.12 × 13.92
  4. Step 4: Simplify right side
    20.40x = 391.43
  5. Step 5: Solve for x
    x = 391.43/20.40
  6. Step 6: Final answer
    x = 19.19

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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.