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Finding the Third Proportional to 312 and 642

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Solution

The third proportional to 312 and 642 is: 1,321.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    312 : 642 = 642 : x
  2. Step 2: Convert to fraction form
    312/642 = 642/x
  3. Step 3: Cross multiply
    312x = 642 × 642
  4. Step 4: Simplify right side
    312x = 412,164
  5. Step 5: Solve for x
    x = 412,164/312
  6. Step 6: Final answer
    x = 1,321.04

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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.