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Finding the Third Proportional to 7.86 and 21.29

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Solution

The third proportional to 7.86 and 21.29 is: 57.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    7.86 : 21.29 = 21.29 : x
  2. Step 2: Convert to fraction form
    7.86/21.29 = 21.29/x
  3. Step 3: Cross multiply
    7.86x = 21.29 × 21.29
  4. Step 4: Simplify right side
    7.86x = 453.12
  5. Step 5: Solve for x
    x = 453.12/7.86
  6. Step 6: Final answer
    x = 57.68

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Why These Related Problems?

These problems maintain the same ratio (2.71) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.