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Finding the Third Proportional to 4.78 and 7.86

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Solution

The third proportional to 4.78 and 7.86 is: 12.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    4.78 : 7.86 = 7.86 : x
  2. Step 2: Convert to fraction form
    4.78/7.86 = 7.86/x
  3. Step 3: Cross multiply
    4.78x = 7.86 × 7.86
  4. Step 4: Simplify right side
    4.78x = 61.74
  5. Step 5: Solve for x
    x = 61.74/4.78
  6. Step 6: Final answer
    x = 12.91

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Why These Related Problems?

These problems maintain the same ratio (1.64) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.