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Finding the Third Proportional to 70 and 140

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Solution

The third proportional to 70 and 140 is: 280

Step by Step Solution

  1. Step 1: Write the proportion equation
    70 : 140 = 140 : x
  2. Step 2: Convert to fraction form
    70/140 = 140/x
  3. Step 3: Cross multiply
    70x = 140 × 140
  4. Step 4: Simplify right side
    70x = 19,600
  5. Step 5: Solve for x
    x = 19,600/70
  6. Step 6: Final answer
    x = 280

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Why These Related Problems?

These problems maintain the same ratio (2) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.