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Finding the Fourth Proportional to 20.57, 28.39 and 13.31

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Solution

The fourth proportional to 20.57, 28.39 and 13.31 is: 18.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.57 : 28.39 = 13.31 : x
  2. Step 2: Convert to fraction form
    20.57/28.39 = 13.31/x
  3. Step 3: Cross multiply
    20.57x = 28.39 × 13.31
  4. Step 4: Simplify right side
    20.57x = 377.96
  5. Step 5: Solve for x
    x = 377.96/20.57
  6. Step 6: Final answer
    x = 18.37

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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.