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Finding the Third Proportional to 78 and 80

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Solution

The third proportional to 78 and 80 is: 82.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    78 : 80 = 80 : x
  2. Step 2: Convert to fraction form
    78/80 = 80/x
  3. Step 3: Cross multiply
    78x = 80 × 80
  4. Step 4: Simplify right side
    78x = 6,400
  5. Step 5: Solve for x
    x = 6,400/78
  6. Step 6: Final answer
    x = 82.05

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Why These Related Problems?

These problems maintain the same ratio (1.03) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.