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Finding the Third Proportional to 4.91 and 7.80

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Solution

The third proportional to 4.91 and 7.80 is: 12.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    4.91 : 7.80 = 7.80 : x
  2. Step 2: Convert to fraction form
    4.91/7.80 = 7.80/x
  3. Step 3: Cross multiply
    4.91x = 7.80 × 7.80
  4. Step 4: Simplify right side
    4.91x = 60.88
  5. Step 5: Solve for x
    x = 60.88/4.91
  6. Step 6: Final answer
    x = 12.39

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Why These Related Problems?

These problems maintain the same ratio (1.59) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.