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Finding the Fourth Proportional to 20.87, 28.79 and 18.56

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Solution

The fourth proportional to 20.87, 28.79 and 18.56 is: 25.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.87 : 28.79 = 18.56 : x
  2. Step 2: Convert to fraction form
    20.87/28.79 = 18.56/x
  3. Step 3: Cross multiply
    20.87x = 28.79 × 18.56
  4. Step 4: Simplify right side
    20.87x = 534.32
  5. Step 5: Solve for x
    x = 534.32/20.87
  6. Step 6: Final answer
    x = 25.61

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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.