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Finding the Third Proportional to 298.90 and 642.09

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Solution

The third proportional to 298.90 and 642.09 is: 1,379.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    298.90 : 642.09 = 642.09 : x
  2. Step 2: Convert to fraction form
    298.90/642.09 = 642.09/x
  3. Step 3: Cross multiply
    298.90x = 642.09 × 642.09
  4. Step 4: Simplify right side
    298.90x = 412,284.38
  5. Step 5: Solve for x
    x = 412,284.38/298.90
  6. Step 6: Final answer
    x = 1,379.35

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Why These Related Problems?

These problems maintain the same ratio (2.15) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.