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Finding the Third Proportional to 686 and 1,420

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Solution

The third proportional to 686 and 1,420 is: 2,939.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    686 : 1,420 = 1,420 : x
  2. Step 2: Convert to fraction form
    686/1,420 = 1,420/x
  3. Step 3: Cross multiply
    686x = 1,420 × 1,420
  4. Step 4: Simplify right side
    686x = 2,016,400
  5. Step 5: Solve for x
    x = 2,016,400/686
  6. Step 6: Final answer
    x = 2,939.36

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Why These Related Problems?

These problems maintain the same ratio (2.07) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.