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Finding the Third Proportional to 21.80 and 51.86

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Solution

The third proportional to 21.80 and 51.86 is: 123.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.80 : 51.86 = 51.86 : x
  2. Step 2: Convert to fraction form
    21.80/51.86 = 51.86/x
  3. Step 3: Cross multiply
    21.80x = 51.86 × 51.86
  4. Step 4: Simplify right side
    21.80x = 2,689.27
  5. Step 5: Solve for x
    x = 2,689.27/21.80
  6. Step 6: Final answer
    x = 123.39

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Why These Related Problems?

These problems maintain the same ratio (2.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.