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Finding the Fourth Proportional to 20.45, 28.17 and 18.72

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Solution

The fourth proportional to 20.45, 28.17 and 18.72 is: 25.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.45 : 28.17 = 18.72 : x
  2. Step 2: Convert to fraction form
    20.45/28.17 = 18.72/x
  3. Step 3: Cross multiply
    20.45x = 28.17 × 18.72
  4. Step 4: Simplify right side
    20.45x = 527.34
  5. Step 5: Solve for x
    x = 527.34/20.45
  6. Step 6: Final answer
    x = 25.78

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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.