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Finding the Third Proportional to 311.75 and 641.50

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Solution

The third proportional to 311.75 and 641.50 is: 1,320.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.75 : 641.50 = 641.50 : x
  2. Step 2: Convert to fraction form
    311.75/641.50 = 641.50/x
  3. Step 3: Cross multiply
    311.75x = 641.50 × 641.50
  4. Step 4: Simplify right side
    311.75x = 411,522.25
  5. Step 5: Solve for x
    x = 411,522.25/311.75
  6. Step 6: Final answer
    x = 1,320.04

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Why These Related Problems?

These problems maintain the same ratio (2.06) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.