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Finding the Third Proportional to 645 and 1,405

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Solution

The third proportional to 645 and 1,405 is: 3,060.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    645 : 1,405 = 1,405 : x
  2. Step 2: Convert to fraction form
    645/1,405 = 1,405/x
  3. Step 3: Cross multiply
    645x = 1,405 × 1,405
  4. Step 4: Simplify right side
    645x = 1,974,025
  5. Step 5: Solve for x
    x = 1,974,025/645
  6. Step 6: Final answer
    x = 3,060.50

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Why These Related Problems?

These problems maintain the same ratio (2.18) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.