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Finding the Third Proportional to 7.87 and 20.21

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Solution

The third proportional to 7.87 and 20.21 is: 51.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    7.87 : 20.21 = 20.21 : x
  2. Step 2: Convert to fraction form
    7.87/20.21 = 20.21/x
  3. Step 3: Cross multiply
    7.87x = 20.21 × 20.21
  4. Step 4: Simplify right side
    7.87x = 408.55
  5. Step 5: Solve for x
    x = 408.55/7.87
  6. Step 6: Final answer
    x = 51.92

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Why These Related Problems?

These problems maintain the same ratio (2.57) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.