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Finding the Third Proportional to 261 and 405

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Solution

The third proportional to 261 and 405 is: 628.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    261 : 405 = 405 : x
  2. Step 2: Convert to fraction form
    261/405 = 405/x
  3. Step 3: Cross multiply
    261x = 405 × 405
  4. Step 4: Simplify right side
    261x = 164,025
  5. Step 5: Solve for x
    x = 164,025/261
  6. Step 6: Final answer
    x = 628.45

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Why These Related Problems?

These problems maintain the same ratio (1.55) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.