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Finding the Third Proportional to 320.20 and 678.80

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Solution

The third proportional to 320.20 and 678.80 is: 1,438.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    320.20 : 678.80 = 678.80 : x
  2. Step 2: Convert to fraction form
    320.20/678.80 = 678.80/x
  3. Step 3: Cross multiply
    320.20x = 678.80 × 678.80
  4. Step 4: Simplify right side
    320.20x = 460,765.20
  5. Step 5: Solve for x
    x = 460,765.20/320.20
  6. Step 6: Final answer
    x = 1,438.98

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Why These Related Problems?

These problems maintain the same ratio (2.12) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.