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Finding the Third Proportional to 13.78 and 20.81

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Solution

The third proportional to 13.78 and 20.81 is: 31.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.78 : 20.81 = 20.81 : x
  2. Step 2: Convert to fraction form
    13.78/20.81 = 20.81/x
  3. Step 3: Cross multiply
    13.78x = 20.81 × 20.81
  4. Step 4: Simplify right side
    13.78x = 433.16
  5. Step 5: Solve for x
    x = 433.16/13.78
  6. Step 6: Final answer
    x = 31.43

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.