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Finding the Third Proportional to 5.11 and 7.80

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Solution

The third proportional to 5.11 and 7.80 is: 11.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    5.11 : 7.80 = 7.80 : x
  2. Step 2: Convert to fraction form
    5.11/7.80 = 7.80/x
  3. Step 3: Cross multiply
    5.11x = 7.80 × 7.80
  4. Step 4: Simplify right side
    5.11x = 60.77
  5. Step 5: Solve for x
    x = 60.77/5.11
  6. Step 6: Final answer
    x = 11.90

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Why These Related Problems?

These problems maintain the same ratio (1.53) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.